Reimplement [PutForwards] per spec

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 93dd7c8e93b4aa240283c6c2d70bc6a8232ac12d..0cd46fd8d8d4c3ca89d90e615b88457b366bdb98 100644
--- a/third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/attributes.cpp.tmpl
@@ -288,6 +288,9 @@ v8::Local<v8::Value> v8Value, const v8::FunctionCallbackInfo<v8::Value>& info
   v8::Isolate* isolate = info.GetIsolate();
   ALLOW_UNUSED_LOCAL(isolate);
 
+  v8::Local<v8::Object> holder = info.Holder();
+  ALLOW_UNUSED_LOCAL(holder);
+
   {% set define_exception_state -%}
   ExceptionState exceptionState(isolate, ExceptionState::kSetterContext, "{{interface_name}}", "{{attribute.name}}");
   {%- endset %}
@@ -295,18 +298,11 @@ v8::Local<v8::Value> v8Value, const v8::FunctionCallbackInfo<v8::Value>& info
   {% if attribute.is_lenient_this %}
   // [LenientThis]
   // Make sure that info.Holder() really points to an instance if [LenientThis].
-  if (!{{v8_class}}::hasInstance(info.Holder(), isolate))
+  if (!{{v8_class}}::hasInstance(holder, isolate))
     return; // Return silently because of [LenientThis].
   {% endif %}
 
-  {% if not attribute.is_static and not attribute.is_replaceable %}
-  v8::Local<v8::Object> holder = info.Holder();
-  {% if attribute.is_put_forwards %}
-  {{cpp_class}}* proxyImpl = {{v8_class}}::toImpl(holder);
-  {{attribute.cpp_type}} impl = WTF::GetPtr(proxyImpl->{{attribute.name}}());
-  if (!impl)
-    return;
-  {% else %}
+  {% if not attribute.is_static and not attribute.is_replaceable and not attribute.is_put_forwards %}
   {% set local_dom_window_only = interface_name == 'Window' and not attribute.has_cross_origin_setter %}
   {% if local_dom_window_only %}
   {% if attribute.is_check_security_for_receiver %}
@@ -321,7 +317,6 @@ v8::Local<v8::Value> v8Value, const v8::FunctionCallbackInfo<v8::Value>& info
   {{cpp_class}}* impl = {{v8_class}}::toImpl(holder);
   {% endif %}{# local_dom_window_only #}
   {% endif %}
-  {% endif %}
 
   {% if attribute.is_check_security_for_receiver and not attribute.is_data_type_property %}
   // Perform a security check for the receiver object.
@@ -343,6 +338,20 @@ v8::Local<v8::Value> v8Value, const v8::FunctionCallbackInfo<v8::Value>& info
 #error Attribute setter with the security check for the return value is not supported.  Since the return value is the given value to be set, it\'s meaningless to perform the security check for the return value.
   {% endif %}
 
+  {% if attribute.is_put_forwards %}
+  // [PutForwards] => {{attribute.name}}.{{attribute.target_attribute_name}}
+  {{define_exception_state}}
+  v8::Local<v8::Value> target;
+  if (!holder->Get(isolate->GetCurrentContext(), V8String(isolate, "{{attribute.name}}")).ToLocal(&target))

[haraken, 2017/05/10 14:40:03]

Just to confirm: If the author script overrides the getter, the customized
getter can be called here. Is that okay?

+    return;
+  if (!target->IsObject()) {
+    exceptionState.ThrowTypeError("The attribute value is not an object");
+    return;
+  }
+  v8::Maybe<bool> result = target.As<v8::Object>()->Set(isolate->GetCurrentContext(), V8String(isolate, "{{attribute.target_attribute_name}}"), v8Value);

[haraken, 2017/05/10 14:40:03]

Ditto. The customized setter can be called.

[haraken, 2017/05/10 14:40:03]

We prefer avoid using Maybe. You can use ...Set().To().

+  if (result.IsNothing() || !result.FromJust())
+    return;
+  {% else %}{# attribute.is_put_forwards #}
   {% if attribute.is_custom_element_callbacks or
         (attribute.is_reflect and not (attribute.idl_type == 'DOMString' and is_node)) %}
   // Skip on compact node DOMString getters.
@@ -408,6 +417,7 @@ v8::Local<v8::Value> v8Value, const v8::FunctionCallbackInfo<v8::Value>& info
       isolate, "{{cpp_class}}#{{attribute.name.capitalize()}}")
       .DeleteProperty(holder, v8::Undefined(isolate));
   {% endif %}
+  {% endif %}{# attribute.is_put_forwards #}
 }
 {% endfilter %}{# format_remove_duplicates #}
 {% endmacro %}