Don't add code dependencies on transitioning stores eagerly.

src/handles.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HANDLES_H_
 #define V8_HANDLES_H_
 
 #include "objects.h"
 
 namespace v8 {
@@ skipping 137 matching lines @@
 }
 
 
 // Convenience wrapper.
 template<class T>
 inline Handle<T> handle(T* t) {
   return Handle<T>(t, t->GetIsolate());
 }
 
 
+// Key comparison function for Map handles.
+inline bool operator<(const Handle<Map>& lhs, const Handle<Map>& rhs) {
+  // This is safe because maps don't move.
+  return *lhs < *rhs;

[mvstanton, 2014/05/02 06:34:16]

Seems like I see MStarzinger cringe every time we encode this assumption
somewhere.

[Benedikt Meurer, 2014/05/02 06:39:15]

Yeah... having some kind of ObjectTraits<T>::IsImmovable() would be nice, that
way we could add STATIC_ASSERT()s everywhere we depend on this...

+}
+
+
 class DeferredHandles;
 class HandleScopeImplementer;
 
 
 // A stack-allocated class that governs a number of local handles.
 // After a handle scope has been created, all local handles will be
 // allocated within that handle scope until either the handle scope is
 // deleted or another handle scope is created.  If there is already a
 // handle scope and a new one is created, all allocations will take
 // place in the new handle scope until it is deleted.  After that,
@@ skipping 113 matching lines @@
 
   void Initialize() {
     next = limit = NULL;
     level = 0;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_HANDLES_H_