bindings: Add empty checks for toV8()

Source/bindings/core/v8/V8Binding.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 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 83 matching lines @@
     exceptionState.throwTypeError(ExceptionMessages::notEnoughArguments(expected, provided));
 }
 
 PassRefPtrWillBeRawPtr<NodeFilter> toNodeFilter(v8::Handle<v8::Value> callback, v8::Handle<v8::Object> creationContext, ScriptState* scriptState)
 {
     if (callback->IsNull())
         return nullptr;
     RefPtrWillBeRawPtr<NodeFilter> filter = NodeFilter::create();
 
     v8::Handle<v8::Object> filterWrapper = toV8(filter.get(), creationContext, scriptState->isolate()).As<v8::Object>();
+    if (filterWrapper.IsEmpty())

[haraken, 2015/04/28 04:24:59]

This is a bit too late to check the emptiness. We need to check it before
calling .As.

[bashi, 2015/04/28 05:41:53]

Done.

+        return nullptr;
 
     RefPtrWillBeRawPtr<NodeFilterCondition> condition = V8NodeFilterCondition::create(callback, filterWrapper, scriptState);
     filter->setCondition(condition.release());
 
     return filter.release();
 }
 
 bool toBooleanSlow(v8::Isolate* isolate, v8::Local<v8::Value> value, ExceptionState& exceptionState)
 {
     ASSERT(!value->IsBoolean());
@@ skipping 873 matching lines @@
     v8::Local<v8::Value> data = info.Data();
     ASSERT(data->IsExternal());
     V8PerContextData* perContextData = V8PerContextData::from(info.Holder()->CreationContext());
     if (!perContextData)
         return;
     v8SetReturnValue(info, perContextData->constructorForType(WrapperTypeInfo::unwrap(data)));
     TRACE_EVENT_SET_SAMPLING_STATE("v8", "V8Execution");
 }
 
 } // namespace blink