[vm/shared] Ensure scratch register is requested as temp for LoadStaticFieldInstr.

TEST=tests/ffi/many_listener_callbacks_test/5 on vm-ffi-qemu-linux-release-arm

Change-Id: I6a60220bce6dbc760e3a027b1b023c59dff36ba7
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/487200
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>

runtime/vm/compiler/backend/il.cc

@@ -4516,7 +4516,7 @@ LocationSummary* LoadStaticFieldInstr::MakeLocationSummary(Zone* zone,
   const intptr_t kNumTemps = does_throw_access_error_or_call_initializer() &&
                                      throw_exception_on_initialization() &&
                                      use_shared_stub
-                                 ? 1
+                                 ? 2
                                  : 0;
   LocationSummary* locs = new (zone) LocationSummary(
       zone, kNumInputs, kNumTemps,
@@ -4530,6 +4530,8 @@ LocationSummary* LoadStaticFieldInstr::MakeLocationSummary(Zone* zone,
       throw_exception_on_initialization() && use_shared_stub) {
     locs->set_temp(
         0, Location::RegisterLocation(LateInitializationErrorABI::kFieldReg));
+    locs->set_temp(1, Location::RegisterLocation(
+                          InitLateStaticFieldInternalRegs::kScratchReg));
   }
   locs->set_out(0,
                 does_throw_access_error_or_call_initializer()

tests/ffi/many_listener_callbacks_test.dart

@@ -11,6 +11,7 @@
 // VMOptions=--use-slow-path --stacktrace-every=100
 // VMOptions=--dwarf_stack_traces --no-retain_function_objects --no-retain_code_objects
 // VMOptions=--test_il_serialization
+// VMOptions=--experimental-shared-data
 // SharedObjects=ffi_test_functions
 
 // No profiler for this test. TSAN's vector clocks become more expensive as the