Reimplement [PutForwards] per spec

third_party/WebKit/Source/bindings/scripts/v8_attributes.py

Index: third_party/WebKit/Source/bindings/scripts/v8_attributes.py
diff --git a/third_party/WebKit/Source/bindings/scripts/v8_attributes.py b/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
index 2ab1aecf129b6a9628e4025987ad33caf3a38aec..b058b6e76120459adc036631dadcd8e06dd0ab52 100644
--- a/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
+++ b/third_party/WebKit/Source/bindings/scripts/v8_attributes.py
@@ -385,19 +385,20 @@ def is_keep_alive_for_gc(interface, attribute):
 
 def setter_context(interface, attribute, interfaces, context):
     if 'PutForwards' in attribute.extended_attributes:
-        # Use target interface and attribute in place of original interface and
-        # attribute from this point onwards.
+        # Make sure the target interface and attribute exist.
         target_interface_name = attribute.idl_type.base_type
         target_attribute_name = attribute.extended_attributes['PutForwards']
         interface = interfaces[target_interface_name]
         try:
-            attribute = next(candidate
-                             for candidate in interface.attributes
-                             if candidate.name == target_attribute_name)
+            next(candidate
+                 for candidate in interface.attributes
+                 if candidate.name == target_attribute_name)
         except StopIteration:
             raise Exception('[PutForward] target not found:\n'
                             'Attribute "%s" is not present in interface "%s"' %
                             (target_attribute_name, target_interface_name))
+        context['target_attribute_name'] = target_attribute_name
+        return
 
     if ('Replaceable' in attribute.extended_attributes):
         context['cpp_setter'] = (