Use mutable heapnumbers to store doubles in fields.

test/cctest/test-heap-profiler.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1396 matching lines @@
   CHECK(js_obj == obj->GetHeapValue());
   const v8::HeapGraphNode* s_prop =
       GetProperty(obj, v8::HeapGraphEdge::kProperty, "s_prop");
   v8::Local<v8::String> js_s_prop =
       js_obj->Get(v8_str("s_prop")).As<v8::String>();
   CHECK(js_s_prop == s_prop->GetHeapValue());
   const v8::HeapGraphNode* n_prop =
       GetProperty(obj, v8::HeapGraphEdge::kProperty, "n_prop");
   v8::Local<v8::Number> js_n_prop =
       js_obj->Get(v8_str("n_prop")).As<v8::Number>();
-  CHECK(js_n_prop == n_prop->GetHeapValue());
+  CHECK(js_n_prop->NumberValue() == n_prop->GetHeapValue()->NumberValue());
 }
 
 
 TEST(GetHeapValueForDeletedObject) {
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());
   v8::HeapProfiler* heap_profiler = env->GetIsolate()->GetHeapProfiler();
 
   // It is impossible to delete a global property, so we are about to delete a
   // property of the "a" object. Also, the "p" object can't be an empty one
@@ skipping 349 matching lines @@
   // Check all the objects have got their names.
   // ... well check just every 8th because otherwise it's too slow in debug.
   for (int i = 0; i < num_objects - 1; i += 8) {
     i::EmbeddedVector<char, 100> var_name;
     i::OS::SNPrintF(var_name, "f_%d", i);
     const v8::HeapGraphNode* f_object = GetProperty(
         context_object, v8::HeapGraphEdge::kContextVariable, var_name.start());
     CHECK_NE(NULL, f_object);
   }
 }