[bindings] Introduce PostMessage extended keyword

Source/bindings/templates/methods.cpp

Index: Source/bindings/templates/methods.cpp
diff --git a/Source/bindings/templates/methods.cpp b/Source/bindings/templates/methods.cpp
index bec96edb174c10a2f3f85a8733cc9d252b4e4f78..5d43cec109b0b7b31911c9a219d339169cc6e1e0 100644
--- a/Source/bindings/templates/methods.cpp
+++ b/Source/bindings/templates/methods.cpp
@@ -471,7 +471,11 @@ static void {{method.name}}MethodCallback{{world_suffix}}(const v8::FunctionCall
     }
     {% endif %}
     {% if method.is_custom %}
+    {% if method.is_post_message_common %}
+    postMessageMethodCommon("{{interface_name}}", {{v8_class}}::toImpl(info.Holder()), info);
+    {% else %}
     {{v8_class}}::{{method.name}}MethodCustom(info);
+    {% endif %}
     {% else %}
     {{cpp_class_or_partial}}V8Internal::{{method.name}}Method{{world_suffix}}(info);
     {% endif %}