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 6630e1129330ccbd17a489cb5c4ef4afd25df3e8..a2d2b3a49a74f81e457bbaebf17e0a736bf9d27c 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8DOMConfiguration.h
@@ -62,6 +62,11 @@ public:
         DoNotCheckHolder,
     };
 
+    typedef v8::experimental::FastAccessorBuilder* (*FastAccessorBuilderCallback)(v8::Isolate*,
+        v8::FunctionCallback); // Default (slow) callback.
+
+    typedef v8::Local<v8::Private> (*CachedAccessorCallback)(v8::Isolate*);
+
     // AttributeConfiguration translates into calls to SetNativeDataProperty() on either
     // the instance or the prototype ObjectTemplate, based on |instanceOrPrototypeConfiguration|.
     struct AttributeConfiguration {
@@ -72,6 +77,8 @@ public:
         v8::AccessorNameSetterCallback setter;
         v8::AccessorNameGetterCallback getterForMainWorld;
         v8::AccessorNameSetterCallback setterForMainWorld;
+        // TODO(peterssen|vogelheim): This has to be removed too since it's only used in accessors.
+        CachedAccessorCallback cachedAccessorCallback; // The accessor's 'result' is stored in a private property.
         const WrapperTypeInfo* data;
         unsigned settings : 8; // v8::AccessControl
         unsigned attribute : 8; // v8::PropertyAttribute
@@ -96,6 +103,7 @@ public:
         v8::FunctionCallback setter;
         v8::FunctionCallback getterForMainWorld;
         v8::FunctionCallback setterForMainWorld;
+        CachedAccessorCallback cachedAccessorCallback; // The accessor's 'result' is stored in a private property.
         const WrapperTypeInfo* data;
         unsigned settings : 8; // v8::AccessControl
         unsigned attribute : 8; // v8::PropertyAttribute