bindings: Supports [LenientThis] extended attributes.

Source/bindings/core/v8/V8DOMConfiguration.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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 84 matching lines @@
         return;
 
     v8::FunctionCallback getterCallback = accessor.getter;
     v8::FunctionCallback setterCallback = accessor.setter;
     if (world.isMainWorld()) {
         if (accessor.getterForMainWorld)
             getterCallback = accessor.getterForMainWorld;
         if (accessor.setterForMainWorld)
             setterCallback = accessor.setterForMainWorld;
     }
+    // Support [LenientThis] by not specifying the signature.  V8 does not do
+    // the type checking against holder if no signature is specified.  Note that
+    // info.Holder() passed to callbacks will be *unsafe*.
+    if (accessor.holderCheckConfiguration == V8DOMConfiguration::DoNotCheckHolder)
+        signature = v8::Local<v8::Signature>();
     prototypeOrTemplate->SetAccessorProperty(
         v8AtomicString(isolate, accessor.name),
         functionOrTemplate(isolate, getterCallback, accessor.data, signature, 0, prototypeOrTemplate),
         functionOrTemplate(isolate, setterCallback, accessor.data, signature, 1, prototypeOrTemplate),
         accessor.attribute,
         accessor.settings);
 }
 
 void installConstantInternal(v8::Isolate* isolate, v8::Local<v8::FunctionTemplate> functionDescriptor, v8::Local<v8::ObjectTemplate> prototypeTemplate, const V8DOMConfiguration::ConstantConfiguration& constant)
 {
@@ skipping 166 matching lines @@
         return result;
 
     TRACE_EVENT_SCOPED_SAMPLING_STATE("blink", "BuildDOMTemplate");
     result = v8::FunctionTemplate::New(isolate, V8ObjectConstructor::isValidConstructorMode);
     configureDOMClassTemplate(result, isolate);
     data->setDOMTemplate(wrapperTypeInfo, result);
     return result;
 }
 
 } // namespace blink