Convert serialized values to ints if they are whole and less than 53 bits.

Source/bindings/dart/V8Converter.cpp

 /*
  * Copyright (C) 2012 Google Inc. 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
@@ skipping 152 matching lines @@
     Dart_Handle result = map.get(value);
     if (result)
         return result;
 
     if (value->IsUndefined())
         return Dart_Null();
     if (value->IsNull())
         return Dart_Null();
     if (value->IsString())
         return map.put(value, stringToDart(value));
-    if (value->IsInt32())
-        return Dart_NewInteger(value->Int32Value());
+    if (value->IsNumber() && abs(value->IntegerValue()) <= pow(2, 53)) {
+        // JS can store integer values that are no greater than 2^53.
+        return Dart_NewInteger(value->IntegerValue());
+    }
     if (value->IsBoolean())
         return Dart_NewBoolean(value->BooleanValue());
     if (value->IsNumber())
         return Dart_NewDouble(value->NumberValue());
     if (value->IsArray())
         return listToDart(value.As<v8::Array>(), map, exception);
     if (value->IsDate())
         return dateToDart(value);
     if (value->IsObject()) {
         v8::Handle<v8::Object> object = value.As<v8::Object>();
@@ skipping 311 matching lines @@
 }
 
 Dart_Handle V8Converter::arrayBufferViewToDart(v8::Handle<v8::Object> object, V8ToDartMap& map, Dart_Handle& exception)
 {
     RefPtr<ArrayBufferView> view = V8ArrayBufferView::toNative(object);
     Dart_Handle result = DartUtilities::arrayBufferViewToDart(view.get());
     return map.put(object, result);
 }
 
 } // namespace WebCore