Factor File API's 'partial interface URL' impl into separate files

third_party/WebKit/Source/bindings/templates/interface.h

Index: third_party/WebKit/Source/bindings/templates/interface.h
diff --git a/third_party/WebKit/Source/bindings/templates/interface.h b/third_party/WebKit/Source/bindings/templates/interface.h
index eb82f589635f76698abe49fcb239bbbb3e7bdc2b..fb5e5a06e958956c8e87fa010199173239e35e19 100644
--- a/third_party/WebKit/Source/bindings/templates/interface.h
+++ b/third_party/WebKit/Source/bindings/templates/interface.h
@@ -151,7 +151,7 @@ public:
     static void installConditionallyEnabledProperties(v8::Local<v8::Object>, v8::Isolate*){% if has_conditional_attributes %};
     {% else %} { }
     {% endif %}
-    static void preparePrototypeAndInterfaceObject(v8::Local<v8::Context>, const DOMWrapperWorld&, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate){% if unscopeables or has_conditional_attributes_on_prototype or conditionally_enabled_methods %};
+    {{exported}}static void preparePrototypeAndInterfaceObject(v8::Local<v8::Context>, const DOMWrapperWorld&, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate){% if unscopeables or has_conditional_attributes_on_prototype or conditionally_enabled_methods %};
     {% else %} { }
     {% endif %}
     {% if has_partial_interface %}