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

third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h

Index: third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h b/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
index 486aa74b6e3dea76e66c0fd37bc3079f99764034..a5be16b5c77d2e819bf16cac96669fc75f8763de 100644
--- a/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
+++ b/third_party/WebKit/Source/bindings/core/v8/V8PrivateProperty.h
@@ -21,20 +21,21 @@ class ScriptState;
 class ScriptWrappable;
 
 // Apply |X| for each pair of (InterfaceName, PrivateKeyName).
-#define V8_PRIVATE_PROPERTY_FOR_EACH(X) \
-    X(CustomEvent, Detail) \
-    X(DOMException, Error) \
-    X(ErrorEvent, Error) \
-    X(IDBObserver, Callback) \
-    X(IntersectionObserver, Callback) \
-    X(MessageEvent, CachedData) \
-    X(MutationObserver, Callback) \
-    X(PerformanceObserver, Callback) \
+#define V8_PRIVATE_PROPERTY_FOR_EACH(X)   \
+    X(CustomEvent, Detail)                \
+    X(DOMException, Error)                \
+    X(ErrorEvent, Error)                  \
+    X(IDBObserver, Callback)              \
+    X(IntersectionObserver, Callback)     \
+    X(MessageEvent, CachedData)           \
+    X(MutationObserver, Callback)         \
+    X(PerformanceObserver, Callback)      \
     X(PrivateScriptRunner, IsInitialized) \
-    X(SameObject, NotificationActions) \
-    X(SameObject, NotificationData) \
-    X(SameObject, NotificationVibrate) \
-    X(V8NodeFilterCondition, Filter)
+    X(SameObject, NotificationActions)    \
+    X(SameObject, NotificationData)       \
+    X(SameObject, NotificationVibrate)    \
+    X(V8NodeFilterCondition, Filter)      \
+    X(Window, DocumentCachedAccessor)
 
 // The getter's name for a private property.
 #define V8_PRIVATE_PROPERTY_GETTER_NAME(InterfaceName, PrivateKeyName) \
@@ -101,6 +102,11 @@ public:
             return v8CallBoolean(object->SetPrivate(context, m_privateSymbol, value));
         }
 
+        v8::Local<v8::Private> getPrivate()
+        {
+            return m_privateSymbol;
+        }
+
     private:
         friend class V8PrivateProperty;
         // The following classes are exceptionally allowed to call to