Change Type::signature to not allocate a handle and instead use the cid value.

runtime/vm/object.cc

 // Copyright (c) 2012, 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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 16372 matching lines @@
   return LanguageError::null();
 }
 
 
 void Type::set_error(const LanguageError& value) const {
   StorePointer(&raw_ptr()->sig_or_err_.error_, value.raw());
 }
 
 
 RawFunction* Type::signature() const {
-  if (raw_ptr()->sig_or_err_.signature_ == Function::null()) {
+  intptr_t cid = raw_ptr()->sig_or_err_.signature_->GetClassId();
+  if (cid == kNullCid) {
     return Function::null();
   }
-  const Object& obj = Object::Handle(raw_ptr()->sig_or_err_.signature_);
-  if (obj.IsFunction()) {
-    return Function::RawCast(obj.raw());
+  if (cid == kFunctionCid) {
+    return Function::RawCast(raw_ptr()->sig_or_err_.signature_);
   }
-  ASSERT(obj.IsLanguageError());  // Type is malformed or malbounded.
+  ASSERT(cid == kLanguageErrorCid);  // Type is malformed or malbounded.
   return Function::null();
 }
 
 
 void Type::set_signature(const Function& value) const {
   StorePointer(&raw_ptr()->sig_or_err_.signature_, value.raw());
 }
 
 
 void Type::SetIsResolved() const {
@@ skipping 5984 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart