Add [CachedAccessor] attribute to cache (almost) constant accessors (window.document).

third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h

Index: third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h b/third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h
index 4e6852c0680c142b1184f2a15d5803c3890ceb2c..6bdf888b26dca433e073479769289ca715cc9743 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h
@@ -65,6 +65,8 @@ public:
     typedef v8::experimental::FastAccessorBuilder* (*FastAccessorBuilderCallback)(v8::Isolate*,
         v8::FunctionCallback); // Default (slow) callback.
 
+    typedef v8::Local<v8::Private> (*PrivatePropertyCallback)(v8::Isolate*);
+
     // AttributeConfiguration translates into calls to SetNativeDataProperty() on either
     // the instance or the prototype ObjectTemplate, based on |instanceOrPrototypeConfiguration|.
     struct AttributeConfiguration {
@@ -75,8 +77,12 @@ public:
         v8::AccessorNameSetterCallback setter;
         v8::AccessorNameGetterCallback getterForMainWorld;
         v8::AccessorNameSetterCallback setterForMainWorld;
-        // TODO(vogelheim): Figure out how to remove this.
+
+        // TODO(peterssen|vogelheim): Figure out how to remove this.
         FastAccessorBuilderCallback fastGetter;
+        // TODO(peterssen|vogelheim): This has to be removed too since it's only used in accessors.
+        PrivatePropertyCallback surrogatePropertyCallback; // The accessor's 'result' is stored in a private property.
+
         const WrapperTypeInfo* data;
         unsigned settings : 8; // v8::AccessControl
         unsigned attribute : 8; // v8::PropertyAttribute
@@ -102,6 +108,7 @@ public:
         v8::FunctionCallback getterForMainWorld;
         v8::FunctionCallback setterForMainWorld;
         FastAccessorBuilderCallback fastGetter;
+        PrivatePropertyCallback surrogatePropertyCallback; // The accessor's 'result' is stored in a private property.
         const WrapperTypeInfo* data;
         unsigned settings : 8; // v8::AccessControl
         unsigned attribute : 8; // v8::PropertyAttribute