bindings: Add empty checks for toV8()

Source/bindings/core/v8/V8CustomElementLifecycleCallbacks.cpp

 /*
  * Copyright (C) 2013 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 138 matching lines @@
         return;
 
     element->setCustomElementState(Element::Upgraded);
 
     ScriptState::Scope scope(m_scriptState.get());
     v8::Isolate* isolate = m_scriptState->isolate();
     v8::Local<v8::Context> context = m_scriptState->context();
     v8::Local<v8::Object> receiver = m_scriptState->world().domDataStore().get(element, isolate);
     if (receiver.IsEmpty())
         receiver = toV8(element, context->Global(), isolate).As<v8::Object>();
+    if (receiver.IsEmpty())
+        return;

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

Not related to your CL, this code is doing something strange. A common patter
would be:

  receiver = DOMDataStore::getWrapper();
  if (receiver.isEmpty())
    receiver = wrap();
  ...

[Yuki, 2015/04/28 04:47:57]

and it should be done inside toV8().

I agree that the current code is faster than a simple call to toV8 because it
already knew the |world| and there is no need to look up the |world|, though.

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

As chatted offline, we can simply use toV8(). Done.

 
     // Swizzle the prototype of the wrapper.
     v8::Local<v8::Object> prototype = m_prototype.newLocal(isolate);
     if (prototype.IsEmpty())
         return;
     if (!v8CallBoolean(receiver->SetPrototype(context, prototype)))
         return;
 
     v8::Local<v8::Function> callback = m_created.newLocal(isolate);
     if (callback.IsEmpty())
@@ skipping 21 matching lines @@
     // Bug 329665 tracks similar behavior for other synchronous events.
     if (!executionContext() || executionContext()->activeDOMObjectsAreStopped())
         return;
 
     if (!m_scriptState->contextIsValid())
         return;
     ScriptState::Scope scope(m_scriptState.get());
     v8::Isolate* isolate = m_scriptState->isolate();
     v8::Local<v8::Context> context = m_scriptState->context();
     v8::Local<v8::Object> receiver = toV8(element, context->Global(), isolate).As<v8::Object>();
-    ASSERT(!receiver.IsEmpty());
+    if (receiver.IsEmpty())
+        return;
 
     v8::Local<v8::Function> callback = m_attributeChanged.newLocal(isolate);
     if (callback.IsEmpty())
         return;
 
     v8::Local<v8::Value> argv[] = {
         v8String(isolate, name),
         oldValue.isNull() ? v8::Local<v8::Value>(v8::Null(isolate)) : v8::Local<v8::Value>(v8String(isolate, oldValue)),
         newValue.isNull() ? v8::Local<v8::Value>(v8::Null(isolate)) : v8::Local<v8::Value>(v8String(isolate, newValue))
     };
@@ skipping 14 matching lines @@
     if (!m_scriptState->contextIsValid())
         return;
     ScriptState::Scope scope(m_scriptState.get());
     v8::Isolate* isolate = m_scriptState->isolate();
     v8::Local<v8::Context> context = m_scriptState->context();
     v8::Local<v8::Function> callback = weakCallback.newLocal(isolate);
     if (callback.IsEmpty())
         return;
 
     v8::Local<v8::Object> receiver = toV8(element, context->Global(), isolate).As<v8::Object>();
-    ASSERT(!receiver.IsEmpty());
+    if (receiver.IsEmpty())

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

Ditto. A bit too late to check the emptiness.

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

Done.

+        return;
 
     v8::TryCatch exceptionCatcher;
     exceptionCatcher.SetVerbose(true);
     ScriptController::callFunction(executionContext(), callback, receiver, 0, 0, isolate);
 }
 
 DEFINE_TRACE(V8CustomElementLifecycleCallbacks)
 {
     CustomElementLifecycleCallbacks::trace(visitor);
     ContextLifecycleObserver::trace(visitor);
 }
 
 } // namespace blink