[gardening] Assert no errors in CompilerState::TypedListClass.

The assert, which is only triggered if we need to generate
calls to the _nativeGetX/_nativeSetX methods, should be checking for
no error, not that there is an error.

TEST=vm-aot-linux-debug-simriscv64 builds

Cq-Include-Trybots: luci.dart.try:vm-aot-linux-debug-simriscv64-try
Change-Id: Ie360a067a6432503fa82ca7eb3d5f9281e0579f0
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/346041
Reviewed-by: Daco Harkes <dacoharkes@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>

runtime/vm/compiler/compiler_state.cc

@@ -139,7 +139,7 @@ const Class& CompilerState::TypedListClass() {
         zone, lib.LookupClassAllowPrivate(Symbols::_TypedList()));
     ASSERT(!cls.IsNull());
     const Error& error = Error::Handle(zone, cls.EnsureIsFinalized(thread));
-    ASSERT(!error.IsNull());
+    ASSERT(error.IsNull());
     typed_list_class_ = &cls;
   }
   return *typed_list_class_;