createTreeWalker and createNodeIterator should deal with null NodeFilter

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 131 matching lines @@
 };
 
 v8::ArrayBuffer::Allocator* v8ArrayBufferAllocator()
 {
     DEFINE_STATIC_LOCAL(ArrayBufferAllocator, arrayBufferAllocator, ());
     return &arrayBufferAllocator;
 }
 
 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, creationContext, scriptState->isolate()).As<v8::Object>();
 
     RefPtrWillBeRawPtr<NodeFilterCondition> condition = V8NodeFilterCondition::create(callback, filterWrapper, scriptState);
     filter->setCondition(condition.release());
 
     return filter.release();
 }
 
@@ skipping 770 matching lines @@
 PassRefPtr<TraceEvent::ConvertableToTraceFormat> devToolsTraceEventData(ExecutionContext* context, v8::Handle<v8::Function> function, v8::Isolate* isolate)
 {
     int scriptId = 0;
     String resourceName;
     int lineNumber = 1;
     GetDevToolsFunctionInfo(function, isolate, scriptId, resourceName, lineNumber);
     return InspectorFunctionCallEvent::data(context, scriptId, resourceName, lineNumber);
 }
 
 } // namespace WebCore