diff --git a/runtime/vm/compiler.cc b/runtime/vm/compiler.cc
index 9c2822a0b67..60a66aba996 100644
--- a/runtime/vm/compiler.cc
+++ b/runtime/vm/compiler.cc
@@ -639,9 +639,9 @@ static void DisassembleCode(const Function& function, bool optimized) {
 
   OS::Print("Pointer offsets for function: {\n");
   // Pointer offsets are stored in descending order.
+  Object& obj = Object::Handle();
   for (intptr_t i = code.pointer_offsets_length() - 1; i >= 0; i--) {
     const uword addr = code.GetPointerOffsetAt(i) + code.EntryPoint();
-    Object& obj = Object::Handle();
     obj = *reinterpret_cast<RawObject**>(addr);
     OS::Print(" %d : %#" Px " '%s'\n",
               code.GetPointerOffsetAt(i), addr, obj.ToCString());
diff --git a/runtime/vm/flow_graph_compiler_arm.cc b/runtime/vm/flow_graph_compiler_arm.cc
index 624ac083d5d..ddd63cb7c86 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -595,7 +595,7 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t token_pos,
     // Generate runtime call.
     // Load instantiator (R2) and its type arguments (R1).
     __ ldm(IA, SP,  (1 << R1) | (1 << R2));
-    __ PushObject(Object::ZoneHandle());  // Make room for the result.
+    __ PushObject(Object::null_object());  // Make room for the result.
     __ Push(R0);  // Push the instance.
     __ PushObject(type);  // Push the type.
     // Push instantiator (R2) and its type arguments (R1).
@@ -661,7 +661,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
 
   // Generate throw new TypeError() if the type is malformed or malbounded.
   if (dst_type.IsMalformedOrMalbounded()) {
-    __ PushObject(Object::ZoneHandle());  // Make room for the result.
+    __ PushObject(Object::null_object());  // Make room for the result.
     __ Push(R0);  // Push the source object.
     __ PushObject(dst_name);  // Push the name of the destination.
     __ PushObject(dst_type);  // Push the type of the destination.
@@ -687,7 +687,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
   __ Bind(&runtime_call);
   // Load instantiator (R2) and its type arguments (R1).
   __ ldm(IA, SP,  (1 << R1) | (1 << R2));
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ Push(R0);  // Push the source object.
   __ PushObject(dst_type);  // Push the type of the destination.
   // Push instantiator (R2) and its type arguments (R1).
diff --git a/runtime/vm/flow_graph_compiler_arm64.cc b/runtime/vm/flow_graph_compiler_arm64.cc
index 3e14d85f5cf..786c1648b57 100644
--- a/runtime/vm/flow_graph_compiler_arm64.cc
+++ b/runtime/vm/flow_graph_compiler_arm64.cc
@@ -588,7 +588,7 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t token_pos,
     // Load instantiator (R2) and its type arguments (R1).
     __ ldr(R1, Address(SP, 0 * kWordSize));
     __ ldr(R2, Address(SP, 1 * kWordSize));
-    __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+    __ PushObject(Object::null_object(), PP);  // Make room for the result.
     __ Push(R0);  // Push the instance.
     __ PushObject(type, PP);  // Push the type.
     // Push instantiator (R2) and its type arguments (R1).
@@ -656,7 +656,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
 
   // Generate throw new TypeError() if the type is malformed or malbounded.
   if (dst_type.IsMalformedOrMalbounded()) {
-    __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+    __ PushObject(Object::null_object(), PP);  // Make room for the result.
     __ Push(R0);  // Push the source object.
     __ PushObject(dst_name, PP);  // Push the name of the destination.
     __ PushObject(dst_type, PP);  // Push the type of the destination.
@@ -684,7 +684,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
   // Load instantiator (R2) and its type arguments (R1).
   __ ldr(R1, Address(SP));
   __ ldr(R2, Address(SP, 1 * kWordSize));
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ Push(R0);  // Push the source object.
   __ PushObject(dst_type, PP);  // Push the type of the destination.
   // Push instantiator (R2) and its type arguments (R1).
diff --git a/runtime/vm/flow_graph_compiler_ia32.cc b/runtime/vm/flow_graph_compiler_ia32.cc
index 2d022c8619b..473f96f6111 100644
--- a/runtime/vm/flow_graph_compiler_ia32.cc
+++ b/runtime/vm/flow_graph_compiler_ia32.cc
@@ -605,7 +605,7 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t token_pos,
     // Generate runtime call.
     __ movl(EDX, Address(ESP, 0));  // Get instantiator type arguments.
     __ movl(ECX, Address(ESP, kWordSize));  // Get instantiator.
-    __ PushObject(Object::ZoneHandle());  // Make room for the result.
+    __ PushObject(Object::null_object());  // Make room for the result.
     __ pushl(EAX);  // Push the instance.
     __ PushObject(type);  // Push the type.
     __ pushl(ECX);  // Instantiator.
@@ -677,7 +677,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
 
   // Generate throw new TypeError() if the type is malformed or malbounded.
   if (dst_type.IsMalformedOrMalbounded()) {
-    __ PushObject(Object::ZoneHandle());  // Make room for the result.
+    __ PushObject(Object::null_object());  // Make room for the result.
     __ pushl(EAX);  // Push the source object.
     __ PushObject(dst_name);  // Push the name of the destination.
     __ PushObject(dst_type);  // Push the type of the destination.
@@ -703,7 +703,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
   __ Bind(&runtime_call);
   __ movl(EDX, Address(ESP, 0));  // Get instantiator type arguments.
   __ movl(ECX, Address(ESP, kWordSize));  // Get instantiator.
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ pushl(EAX);  // Push the source object.
   __ PushObject(dst_type);  // Push the type of the destination.
   __ pushl(ECX);  // Instantiator.
diff --git a/runtime/vm/flow_graph_compiler_mips.cc b/runtime/vm/flow_graph_compiler_mips.cc
index 85b2ef1a293..8041aa57140 100644
--- a/runtime/vm/flow_graph_compiler_mips.cc
+++ b/runtime/vm/flow_graph_compiler_mips.cc
@@ -593,7 +593,7 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t token_pos,
     __ lw(A2, Address(SP, 1 * kWordSize));
 
     __ addiu(SP, SP, Immediate(-6 * kWordSize));
-    __ LoadObject(TMP, Object::ZoneHandle());
+    __ LoadObject(TMP, Object::null_object());
     __ sw(TMP, Address(SP, 5 * kWordSize));  // Make room for the result.
     __ sw(A0, Address(SP, 4 * kWordSize));  // Push the instance.
     __ LoadObject(TMP, type);
@@ -666,7 +666,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
   // Generate throw new TypeError() if the type is malformed or malbounded.
   if (dst_type.IsMalformedOrMalbounded()) {
     __ addiu(SP, SP, Immediate(-4 * kWordSize));
-    __ LoadObject(TMP, Object::ZoneHandle());
+    __ LoadObject(TMP, Object::null_object());
     __ sw(TMP, Address(SP, 3 * kWordSize));  // Make room for the result.
     __ sw(A0, Address(SP, 2 * kWordSize));  // Push the source object.
     __ LoadObject(TMP, dst_name);
@@ -701,7 +701,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
   __ lw(A2, Address(SP, 1 * kWordSize));
 
   __ addiu(SP, SP, Immediate(-7 * kWordSize));
-  __ LoadObject(TMP, Object::ZoneHandle());
+  __ LoadObject(TMP, Object::null_object());
   __ sw(TMP, Address(SP, 6 * kWordSize));  // Make room for the result.
   __ sw(A0, Address(SP, 5 * kWordSize));  // Push the source object.
   __ LoadObject(TMP, dst_type);
diff --git a/runtime/vm/flow_graph_compiler_x64.cc b/runtime/vm/flow_graph_compiler_x64.cc
index d61deea7128..a601029d561 100644
--- a/runtime/vm/flow_graph_compiler_x64.cc
+++ b/runtime/vm/flow_graph_compiler_x64.cc
@@ -594,7 +594,7 @@ void FlowGraphCompiler::GenerateInstanceOf(intptr_t token_pos,
     // Generate runtime call.
     __ movq(RDX, Address(RSP, 0));  // Get instantiator type arguments.
     __ movq(RCX, Address(RSP, kWordSize));  // Get instantiator.
-    __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+    __ PushObject(Object::null_object(), PP);  // Make room for the result.
     __ pushq(RAX);  // Push the instance.
     __ PushObject(type, PP);  // Push the type.
     __ pushq(RCX);  // TODO(srdjan): Pass instantiator instead of null.
@@ -664,7 +664,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
 
   // Generate throw new TypeError() if the type is malformed or malbounded.
   if (dst_type.IsMalformedOrMalbounded()) {
-    __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+    __ PushObject(Object::null_object(), PP);  // Make room for the result.
     __ pushq(RAX);  // Push the source object.
     __ PushObject(dst_name, PP);  // Push the name of the destination.
     __ PushObject(dst_type, PP);  // Push the type of the destination.
@@ -690,7 +690,7 @@ void FlowGraphCompiler::GenerateAssertAssignable(intptr_t token_pos,
   __ Bind(&runtime_call);
   __ movq(RDX, Address(RSP, 0));  // Get instantiator type arguments.
   __ movq(RCX, Address(RSP, kWordSize));  // Get instantiator.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ pushq(RAX);  // Push the source object.
   __ PushObject(dst_type, PP);  // Push the type of the destination.
   __ pushq(RCX);  // Instantiator.
diff --git a/runtime/vm/intermediate_language_arm.cc b/runtime/vm/intermediate_language_arm.cc
index 16b898a84b9..2c0e4c1c721 100644
--- a/runtime/vm/intermediate_language_arm.cc
+++ b/runtime/vm/intermediate_language_arm.cc
@@ -913,7 +913,7 @@ void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const Register result = locs()->out(0).reg();
 
   // Push the result place holder initialized to NULL.
-  __ PushObject(Object::ZoneHandle());
+  __ PushObject(Object::null_object());
   // Pass a pointer to the first argument in R2.
   if (!function().HasOptionalParameters()) {
     __ AddImmediate(R2, FP, (kParamEndSlotFromFp +
@@ -2367,7 +2367,7 @@ void CreateArrayInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       Label slow_path, done;
       InlineArrayAllocation(compiler, length, &slow_path, &done);
       __ Bind(&slow_path);
-      __ PushObject(Object::ZoneHandle());  // Make room for the result.
+      __ PushObject(Object::null_object());  // Make room for the result.
       __ Push(kLengthReg);  // length.
       __ Push(kElemTypeReg);
       compiler->GenerateRuntimeCall(token_pos(),
@@ -2665,7 +2665,7 @@ void InstantiateTypeInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 
   // 'instantiator_reg' is the instantiator TypeArguments object (or null).
   // A runtime call to instantiate the type is required.
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ PushObject(type());
   __ Push(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2734,7 +2734,7 @@ void InstantiateTypeArgumentsInstr::EmitNativeCode(
   __ Bind(&slow_case);
   // Instantiate non-null type arguments.
   // A runtime call to instantiate the type arguments is required.
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ PushObject(type_arguments());
   __ Push(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2790,7 +2790,7 @@ void CloneContextInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const Register context_value = locs()->in(0).reg();
   const Register result = locs()->out(0).reg();
 
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ Push(context_value);
   compiler->GenerateRuntimeCall(token_pos(),
                                 deopt_id(),
diff --git a/runtime/vm/intermediate_language_arm64.cc b/runtime/vm/intermediate_language_arm64.cc
index 8b8fa14ba7c..f91f4e72477 100644
--- a/runtime/vm/intermediate_language_arm64.cc
+++ b/runtime/vm/intermediate_language_arm64.cc
@@ -758,7 +758,7 @@ void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const Register result = locs()->out(0).reg();
 
   // Push the result place holder initialized to NULL.
-  __ PushObject(Object::ZoneHandle(), PP);
+  __ PushObject(Object::null_object(), PP);
   // Pass a pointer to the first argument in R2.
   if (!function().HasOptionalParameters()) {
     __ AddImmediate(R2, FP, (kParamEndSlotFromFp +
@@ -2241,7 +2241,7 @@ void InstantiateTypeInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 
   // 'instantiator_reg' is the instantiator TypeArguments object (or null).
   // A runtime call to instantiate the type is required.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ PushObject(type(), PP);
   __ Push(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2309,7 +2309,7 @@ void InstantiateTypeArgumentsInstr::EmitNativeCode(
   __ Bind(&slow_case);
   // Instantiate non-null type arguments.
   // A runtime call to instantiate the type arguments is required.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ PushObject(type_arguments(), PP);
   __ Push(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2365,7 +2365,7 @@ void CloneContextInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const Register context_value = locs()->in(0).reg();
   const Register result = locs()->out(0).reg();
 
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ Push(context_value);
   compiler->GenerateRuntimeCall(token_pos(),
                                 deopt_id(),
diff --git a/runtime/vm/intermediate_language_ia32.cc b/runtime/vm/intermediate_language_ia32.cc
index 476aa94b249..cb9a8409100 100644
--- a/runtime/vm/intermediate_language_ia32.cc
+++ b/runtime/vm/intermediate_language_ia32.cc
@@ -803,7 +803,7 @@ void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   StubCode* stub_code = compiler->isolate()->stub_code();
 
   // Push the result place holder initialized to NULL.
-  __ PushObject(Object::ZoneHandle());
+  __ PushObject(Object::null_object());
   // Pass a pointer to the first argument in EAX.
   if (!function().HasOptionalParameters()) {
     __ leal(EAX, Address(EBP, (kParamEndSlotFromFp +
@@ -2170,7 +2170,7 @@ void CreateArrayInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       Label slow_path, done;
       InlineArrayAllocation(compiler, length, &slow_path, &done);
       __ Bind(&slow_path);
-      __ PushObject(Object::ZoneHandle());  // Make room for the result.
+      __ PushObject(Object::null_object());  // Make room for the result.
       __ pushl(kLengthReg);
       __ pushl(kElemTypeReg);
       compiler->GenerateRuntimeCall(token_pos(),
@@ -2468,7 +2468,7 @@ void InstantiateTypeInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 
   // 'instantiator_reg' is the instantiator TypeArguments object (or null).
   // A runtime call to instantiate the type is required.
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ PushObject(type());
   __ pushl(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2540,7 +2540,7 @@ void InstantiateTypeArgumentsInstr::EmitNativeCode(
   __ Bind(&slow_case);
   // Instantiate non-null type arguments.
   // A runtime call to instantiate the type arguments is required.
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ PushObject(type_arguments());
   __ pushl(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2707,7 +2707,7 @@ void CloneContextInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register context_value = locs()->in(0).reg();
   Register result = locs()->out(0).reg();
 
-  __ PushObject(Object::ZoneHandle());  // Make room for the result.
+  __ PushObject(Object::null_object());  // Make room for the result.
   __ pushl(context_value);
   compiler->GenerateRuntimeCall(token_pos(),
                                 deopt_id(),
diff --git a/runtime/vm/intermediate_language_mips.cc b/runtime/vm/intermediate_language_mips.cc
index 62e531b001a..13f5bde2708 100644
--- a/runtime/vm/intermediate_language_mips.cc
+++ b/runtime/vm/intermediate_language_mips.cc
@@ -868,7 +868,7 @@ void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register result = locs()->out(0).reg();
 
   // Push the result place holder initialized to NULL.
-  __ PushObject(Object::ZoneHandle());
+  __ PushObject(Object::null_object());
   // Pass a pointer to the first argument in A2.
   if (!function().HasOptionalParameters()) {
     __ AddImmediate(A2, FP, (kParamEndSlotFromFp +
@@ -2099,7 +2099,7 @@ void CreateArrayInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       Label slow_path, done;
       InlineArrayAllocation(compiler, length, &slow_path, &done);
       __ Bind(&slow_path);
-      __ PushObject(Object::ZoneHandle());  // Make room for the result.
+      __ PushObject(Object::null_object());  // Make room for the result.
       __ Push(kLengthReg);  // length.
       __ Push(kElemTypeReg);
       compiler->GenerateRuntimeCall(token_pos(),
@@ -2280,7 +2280,7 @@ void InstantiateTypeInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   // 'instantiator_reg' is the instantiator TypeArguments object (or null).
   // A runtime call to instantiate the type is required.
   __ addiu(SP, SP, Immediate(-3 * kWordSize));
-  __ LoadObject(TMP, Object::ZoneHandle());
+  __ LoadObject(TMP, Object::null_object());
   __ sw(TMP, Address(SP, 2 * kWordSize));  // Make room for the result.
   __ LoadObject(TMP, type());
   __ sw(TMP, Address(SP, 1 * kWordSize));
@@ -2354,7 +2354,7 @@ void InstantiateTypeArgumentsInstr::EmitNativeCode(
   // Instantiate non-null type arguments.
   // A runtime call to instantiate the type arguments is required.
   __ addiu(SP, SP, Immediate(-3 * kWordSize));
-  __ LoadObject(TMP, Object::ZoneHandle());
+  __ LoadObject(TMP, Object::null_object());
   __ sw(TMP, Address(SP, 2 * kWordSize));  // Make room for the result.
   __ LoadObject(TMP, type_arguments());
   __ sw(TMP, Address(SP, 1 * kWordSize));
@@ -2421,7 +2421,7 @@ void CloneContextInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   __ TraceSimMsg("CloneContextInstr");
 
   __ addiu(SP, SP, Immediate(-2 * kWordSize));
-  __ LoadObject(TMP, Object::ZoneHandle());  // Make room for the result.
+  __ LoadObject(TMP, Object::null_object());  // Make room for the result.
   __ sw(TMP, Address(SP, 1 * kWordSize));
   __ sw(context_value, Address(SP, 0 * kWordSize));
 
diff --git a/runtime/vm/intermediate_language_x64.cc b/runtime/vm/intermediate_language_x64.cc
index 7bcb510bcf4..1798f98239b 100644
--- a/runtime/vm/intermediate_language_x64.cc
+++ b/runtime/vm/intermediate_language_x64.cc
@@ -730,7 +730,7 @@ void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   StubCode* stub_code = compiler->isolate()->stub_code();
 
   // Push the result place holder initialized to NULL.
-  __ PushObject(Object::ZoneHandle(), PP);
+  __ PushObject(Object::null_object(), PP);
   // Pass a pointer to the first argument in RAX.
   if (!function().HasOptionalParameters()) {
     __ leaq(RAX, Address(RBP, (kParamEndSlotFromFp +
@@ -2004,7 +2004,7 @@ void CreateArrayInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
       Label slow_path, done;
       InlineArrayAllocation(compiler, length, &slow_path, &done);
       __ Bind(&slow_path);
-      __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+      __ PushObject(Object::null_object(), PP);  // Make room for the result.
       __ pushq(kLengthReg);
       __ pushq(kElemTypeReg);
       compiler->GenerateRuntimeCall(token_pos(),
@@ -2299,7 +2299,7 @@ void InstantiateTypeInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
 
   // 'instantiator_reg' is the instantiator TypeArguments object (or null).
   // A runtime call to instantiate the type is required.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ PushObject(type(), PP);
   __ pushq(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2370,7 +2370,7 @@ void InstantiateTypeArgumentsInstr::EmitNativeCode(
   __ Bind(&slow_case);
   // Instantiate non-null type arguments.
   // A runtime call to instantiate the type arguments is required.
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ PushObject(type_arguments(), PP);
   __ pushq(instantiator_reg);  // Push instantiator type arguments.
   compiler->GenerateRuntimeCall(token_pos(),
@@ -2427,7 +2427,7 @@ void CloneContextInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register context_value = locs()->in(0).reg();
   Register result = locs()->out(0).reg();
 
-  __ PushObject(Object::ZoneHandle(), PP);  // Make room for the result.
+  __ PushObject(Object::null_object(), PP);  // Make room for the result.
   __ pushq(context_value);
   compiler->GenerateRuntimeCall(token_pos(),
                                 deopt_id(),
diff --git a/runtime/vm/parser.cc b/runtime/vm/parser.cc
index e4c62363e1f..a82fff7c43f 100644
--- a/runtime/vm/parser.cc
+++ b/runtime/vm/parser.cc
@@ -1329,7 +1329,7 @@ void Parser::BuildDispatcherScope(const Function& func,
     intptr_t index = i - desc.PositionalCount();
     p.name = &String::ZoneHandle(I, desc.NameAt(index));
     p.type = &Type::ZoneHandle(I, Type::DynamicType());
-    p.default_value = &Object::ZoneHandle();
+    p.default_value = &Object::null_object();
     params.parameters->Add(p);
     params.num_optional_parameters++;
     params.has_optional_named_parameters = true;
@@ -1697,7 +1697,7 @@ void Parser::ParseFormalParameter(bool allow_explicit_default_value,
         params->has_optional_named_parameters) {
       // Implicit default value is null.
       params->num_optional_parameters++;
-      parameter.default_value = &Object::ZoneHandle();
+      parameter.default_value = &Object::null_object();
     } else {
       params->num_fixed_parameters++;
       ASSERT(params->num_optional_parameters == 0);
diff --git a/runtime/vm/stub_code_arm64_test.cc b/runtime/vm/stub_code_arm64_test.cc
index fa12a56dedf..1011567bf74 100644
--- a/runtime/vm/stub_code_arm64_test.cc
+++ b/runtime/vm/stub_code_arm64_test.cc
@@ -44,12 +44,11 @@ static void GenerateCallToCallRuntimeStub(Assembler* assembler,
   const int argc = 2;
   const Smi& smi1 = Smi::ZoneHandle(Smi::New(value1));
   const Smi& smi2 = Smi::ZoneHandle(Smi::New(value2));
-  const Object& result = Object::ZoneHandle();
   const Context& context = Context::ZoneHandle(Context::New(0, Heap::kOld));
   ASSERT(context.isolate() == Isolate::Current());
   __ EnterDartFrame(0);
   __ LoadObject(CTX, context, PP);
-  __ PushObject(result, PP);  // Push Null object for return value.
+  __ PushObject(Object::null_object(), PP);  // Push Null obj for return value.
   __ PushObject(smi1, PP);  // Push argument 1 smi1.
   __ PushObject(smi2, PP);  // Push argument 2 smi2.
   ASSERT(kTestSmiSubRuntimeEntry.argument_count() == argc);
diff --git a/runtime/vm/stub_code_arm_test.cc b/runtime/vm/stub_code_arm_test.cc
index 490b0d33478..5fa5b2ab743 100644
--- a/runtime/vm/stub_code_arm_test.cc
+++ b/runtime/vm/stub_code_arm_test.cc
@@ -44,12 +44,11 @@ static void GenerateCallToCallRuntimeStub(Assembler* assembler,
   const int argc = 2;
   const Smi& smi1 = Smi::ZoneHandle(Smi::New(value1));
   const Smi& smi2 = Smi::ZoneHandle(Smi::New(value2));
-  const Object& result = Object::ZoneHandle();
   const Context& context = Context::ZoneHandle(Context::New(0, Heap::kOld));
   ASSERT(context.isolate() == Isolate::Current());
   __ EnterDartFrame(0);
   __ LoadObject(CTX, context);
-  __ PushObject(result);  // Push Null object for return value.
+  __ PushObject(Object::null_object());  // Push Null object for return value.
   __ PushObject(smi1);  // Push argument 1 smi1.
   __ PushObject(smi2);  // Push argument 2 smi2.
   ASSERT(kTestSmiSubRuntimeEntry.argument_count() == argc);
diff --git a/runtime/vm/stub_code_ia32_test.cc b/runtime/vm/stub_code_ia32_test.cc
index 796ed752413..baf8f15fc8b 100644
--- a/runtime/vm/stub_code_ia32_test.cc
+++ b/runtime/vm/stub_code_ia32_test.cc
@@ -44,12 +44,11 @@ static void GenerateCallToCallRuntimeStub(Assembler* assembler,
   const int argc = 2;
   const Smi& smi1 = Smi::ZoneHandle(Smi::New(value1));
   const Smi& smi2 = Smi::ZoneHandle(Smi::New(value2));
-  const Object& result = Object::ZoneHandle();
   const Context& context = Context::ZoneHandle(Context::New(0, Heap::kOld));
   ASSERT(context.isolate() == Isolate::Current());
   __ enter(Immediate(0));
   __ LoadObject(CTX, context);
-  __ PushObject(result);  // Push Null object for return value.
+  __ PushObject(Object::null_object());  // Push Null object for return value.
   __ PushObject(smi1);  // Push argument 1 smi1.
   __ PushObject(smi2);  // Push argument 2 smi2.
   ASSERT(kTestSmiSubRuntimeEntry.argument_count() == argc);
diff --git a/runtime/vm/stub_code_mips_test.cc b/runtime/vm/stub_code_mips_test.cc
index a5dd2f1e0cb..00c511218ea 100644
--- a/runtime/vm/stub_code_mips_test.cc
+++ b/runtime/vm/stub_code_mips_test.cc
@@ -44,12 +44,11 @@ static void GenerateCallToCallRuntimeStub(Assembler* assembler,
   const int argc = 2;
   const Smi& smi1 = Smi::ZoneHandle(Smi::New(value1));
   const Smi& smi2 = Smi::ZoneHandle(Smi::New(value2));
-  const Object& result = Object::ZoneHandle();
   const Context& context = Context::ZoneHandle(Context::New(0, Heap::kOld));
   ASSERT(context.isolate() == Isolate::Current());
   __ EnterDartFrame(0);
   __ LoadObject(CTX, context);
-  __ PushObject(result);  // Push Null object for return value.
+  __ PushObject(Object::null_object());  // Push Null object for return value.
   __ PushObject(smi1);  // Push argument 1 smi1.
   __ PushObject(smi2);  // Push argument 2 smi2.
   ASSERT(kTestSmiSubRuntimeEntry.argument_count() == argc);
diff --git a/runtime/vm/stub_code_x64_test.cc b/runtime/vm/stub_code_x64_test.cc
index 56b56fc2822..fb70f91907f 100644
--- a/runtime/vm/stub_code_x64_test.cc
+++ b/runtime/vm/stub_code_x64_test.cc
@@ -44,12 +44,11 @@ static void GenerateCallToCallRuntimeStub(Assembler* assembler,
   const int argc = 2;
   const Smi& smi1 = Smi::ZoneHandle(Smi::New(value1));
   const Smi& smi2 = Smi::ZoneHandle(Smi::New(value2));
-  const Object& result = Object::ZoneHandle();
   const Context& context = Context::ZoneHandle(Context::New(0, Heap::kOld));
   ASSERT(context.isolate() == Isolate::Current());
   __ EnterStubFrame(true);
   __ LoadObject(CTX, context, PP);
-  __ PushObject(result, PP);  // Push Null object for return value.
+  __ PushObject(Object::null_object(), PP);  // Push Null obj for return value.
   __ PushObject(smi1, PP);  // Push argument 1 smi1.
   __ PushObject(smi2, PP);  // Push argument 2 smi2.
   ASSERT(kTestSmiSubRuntimeEntry.argument_count() == argc);