VM: Use read-only handle Object::dynamic_type() where possible.

runtime/vm/ast_transformer.cc

 // Copyright (c) 2014, 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/ast_transformer.h"
 
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/thread.h"
 
@@ skipping 53 matching lines @@
 LocalVariable* AwaitTransformer::EnsureCurrentTempVar() {
   String& symbol =
       String::ZoneHandle(Z, Symbols::NewFormatted("%d", temp_cnt_));
   symbol = Symbols::FromConcat(Symbols::AwaitTempVarPrefix(), symbol);
   ASSERT(!symbol.IsNull());
   // Look up the variable in the scope used for async temp variables.
   LocalVariable* await_tmp = async_temp_scope_->LocalLookupVariable(symbol);
   if (await_tmp == NULL) {
     // We need a new temp variable; add it to the function's top scope.
     await_tmp = new (Z) LocalVariable(
-        Scanner::kNoSourcePos, symbol, Type::ZoneHandle(Type::DynamicType()));
+        Scanner::kNoSourcePos, symbol, Object::dynamic_type());
     async_temp_scope_->AddVariable(await_tmp);
     // After adding it to the top scope, we can look it up from the preamble.
     // The following call includes an ASSERT check.
     await_tmp = GetVariableInScope(preamble_->scope(), symbol);
   }
   return await_tmp;
 }
 
 
 LocalVariable* AwaitTransformer::GetVariableInScope(LocalScope* scope,
@@ skipping 501 matching lines @@
 
 
 void AwaitTransformer::VisitThrowNode(ThrowNode* node) {
   AstNode* new_exception = Transform(node->exception());
   result_ = new(Z) ThrowNode(node->token_pos(),
                              new_exception,
                              node->stacktrace());
 }
 
 }  // namespace dart