Introduce [Abstract] to mark non-leaf interfaces

Some interfaces like Node, CharacterData and HTMLTableCellElement are never
instantiated directly, only their descendant interfaces are. Those are marked
with [Abstract] to set their type_id to None instead of having dummy values
in the TypeId enums.

components/script/dom/bindings/codegen/parser/update.sh

@@ -1,3 +1,4 @@
 wget https://mxr.mozilla.org/mozilla-central/source/dom/bindings/parser/WebIDL.py?raw=1 -O WebIDL.py
 patch < external.patch
 patch < module.patch
+patch < abstract.patch