saves.
* Fast-load file saves the language ID to the fast-load stream, then
delegates the serialization to nsIScriptContext.
* scripttype="..." can be specified at the root of any XUL object. This is
stored in the nsXULPrototypeElement so overlay loading honours the default
script language in the originating document.
* nsXULPrototypeScript now stored the language ID, not the nsIScriptContext.
* The few existing GC assumptions have been abstracted to nsILanguageRuntime
so no nsIScriptContext need be available. This still needs more thought.
git-svn-id: svn://10.0.0.236/branches/DOM_AGNOSTIC_BRANCH@179888 18797224-902f-48f8-a5cc-f745e15eee43
617c48e981