Fix canonicalization of types.

runtime/vm/code_generator.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/code_generator.h"
 
 #include "vm/assembler.h"
 #include "vm/ast.h"
 #include "vm/bigint_operations.h"
 #include "vm/code_patcher.h"
@@ skipping 183 matching lines @@
           String::New(bound_error.ToErrorCString()));
       Exceptions::CreateAndThrowTypeError(
           location, Symbols::Empty(), Symbols::Empty(),
           Symbols::Empty(), bound_error_message);
       UNREACHABLE();
     }
   } else {
     type_arguments =
         type_arguments.InstantiateAndCanonicalizeFrom(instantiator, NULL);
   }
-  ASSERT(type_arguments.IsInstantiated());
+  ASSERT(type_arguments.IsNull() || type_arguments.IsInstantiated());
   arguments.SetReturn(type_arguments);
 }
 
 
 // Allocate a new context large enough to hold the given number of variables.
 // Arg0: number of variables.
 // Return value: newly allocated context.
 DEFINE_RUNTIME_ENTRY(AllocateContext, 1) {
   const Smi& num_variables = Smi::CheckedHandle(arguments.ArgAt(0));
   arguments.SetReturn(Context::Handle(Context::New(num_variables.Value())));
@@ skipping 1333 matching lines @@
 // of the given value.
 //   Arg0: Field object;
 //   Arg1: Value that is being stored.
 DEFINE_RUNTIME_ENTRY(UpdateFieldCid, 2) {
   const Field& field = Field::CheckedHandle(arguments.ArgAt(0));
   const Object& value = Object::Handle(arguments.ArgAt(1));
   field.UpdateGuardedCidAndLength(value);
 }
 
 }  // namespace dart