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

Source/bindings/dart/V8Converter.cpp

Index: Source/bindings/dart/V8Converter.cpp
diff --git a/Source/bindings/dart/V8Converter.cpp b/Source/bindings/dart/V8Converter.cpp
index dd399ffb241fbd9f611929765f23af4a9e0154d6..0c0027b403012a2fd9b163f49cc516ce55e29b39 100644
--- a/Source/bindings/dart/V8Converter.cpp
+++ b/Source/bindings/dart/V8Converter.cpp
@@ -170,8 +170,8 @@ Dart_Handle V8Converter::toDart(v8::Handle<v8::Value> value, V8ToDartMap& map, D
         return Dart_Null();
     if (value->IsString())
         return map.put(value, stringToDart(value));
-    if (value->IsInt32())
-        return Dart_NewInteger(value->Int32Value());
+    if (value->IsNumber() && value->IntegerValue() <= kJSMaxInteger && value->IntegerValue() >= -kJSMaxInteger)
+        return Dart_NewInteger(value->IntegerValue());
     if (value->IsBoolean())
         return Dart_NewBoolean(value->BooleanValue());
     if (value->IsNumber())