Special-case LocalDOMWindow for same-origin access in bindings.

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

Index: third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl
diff --git a/third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl b/third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl
index 5acc271f5b09ce22838c48f5bbefb94d0b58689a..8859c99a18ff1fd75d57130a632231878dab7a15 100644
--- a/third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl
@@ -43,8 +43,15 @@ const v8::FunctionCallbackInfo<v8::Value>& info
   {% endif %}
 
   {% if not attribute.is_static %}
+  {% if interface_name == 'Window' and not attribute.has_cross_origin_getter %}
+  // Same-origin attribute getters are never exposed via the cross-origin
+  // interceptors. Since same-origin access requires a LocalDOMWindow, it is
+  // safe to downcast here.
+  LocalDOMWindow* impl = toLocalDOMWindow({{v8_class}}::toImpl(holder));
+  {% else %}
   {{cpp_class}}* impl = {{v8_class}}::toImpl(holder);
   {% endif %}
+  {% endif %}
 
   {% if attribute.cached_attribute_validation_method %}
   // [CachedAttribute]
@@ -282,9 +289,16 @@ v8::Local<v8::Value> v8Value, const v8::FunctionCallbackInfo<v8::Value>& info
   if (!impl)
     return;
   {% else %}
+  {% if interface_name == 'Window' and not attribute.has_cross_origin_setter %}
+  // Same-origin attribute setters are never exposed via the cross-origin
+  // interceptors. Since same-origin access requires a LocalDOMWindow, it is
+  // safe to downcast here.
+  LocalDOMWindow* impl = toLocalDOMWindow({{v8_class}}::toImpl(holder));
+  {% else %}
   {{cpp_class}}* impl = {{v8_class}}::toImpl(holder);
   {% endif %}
   {% endif %}
+  {% endif %}
 
   {% if attribute.is_check_security_for_receiver and not attribute.is_data_type_property %}
   // Perform a security check for the receiver object.