Implement cross-origin attributes using access check interceptors.

third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl

Index: third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
diff --git a/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl b/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
index 573953a7913e8eeb0c8f41a1b6c6b724c24a3a9f..f0efad808514bafae37e07749b142518e3ce5f4d 100644
--- a/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/methods.cpp.tmpl
@@ -520,6 +520,9 @@ void {{method.name}}MethodCallback{{world_suffix}}(const v8::FunctionCallbackInf
 
 {##############################################################################}
 {% macro origin_safe_method_getter(method, world_suffix) %}
+{# TODO(dcheng): This shouldn't be necessary with cross-origin interceptors, but
+   v8 doesn't support querying the incumbent context. For now, always

[Yuki, 2016/12/07 12:03:41]

ditto

+   incorrectly create per-realm representations. #}
 static void {{method.name}}OriginSafeMethodGetter{{world_suffix}}(const v8::PropertyCallbackInfo<v8::Value>& info) {
   static int domTemplateKey; // This address is used for a key to look up the dom template.
   V8PerIsolateData* data = V8PerIsolateData::from(info.GetIsolate());