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..24bd55a90b945d53cb2f3ab87dc40e3050f6c950 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*);

[haraken, 2016/09/20 14:15:03]

PrivatePropertyCallback => CachedAccessorCallback ?

+
     // 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 cachePropertyCallback; // The accessor's 'result' is stored in a private property.

[haraken, 2016/09/20 14:15:03]

cachedAccessorCallback ?

+
         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 cachePropertyCallback; // The accessor's 'result' is stored in a private property.

[haraken, 2016/09/20 14:15:03]

cachedAccessorCallback ?

         const WrapperTypeInfo* data;
         unsigned settings : 8; // v8::AccessControl
         unsigned attribute : 8; // v8::PropertyAttribute