[VM/compiler] Dereference TypeRef literal when propagating constants.

This fixes #42753

Change-Id: Ibb179c0cf45c77d5b1f29a75ca2dea88d449ed99
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/155503
Reviewed-by: Alexander Markov <[email protected]>
Commit-Queue: Régis Crelier <[email protected]>

Author: crelier

runtime/vm/compiler/backend/constant_propagator.cc

@@ -1024,6 +1024,9 @@ void ConstantPropagator::VisitInstantiateType(InstantiateTypeInstr* instr) {
   AbstractType& result = AbstractType::Handle(
       Z, instr->type().InstantiateFrom(
              instantiator_type_args, function_type_args, kAllFree, Heap::kOld));
+  if (result.IsTypeRef()) {
+    result = TypeRef::Cast(result).type();
+  }
   ASSERT(result.IsInstantiated());
   result = result.Canonicalize();
   SetValue(instr, result);