* When merging overlays, use the default script language specified
in the overlay for attributes, and eagerly compile them if the language
is not the nodes default.
* Remove mLangID from nsIXULPrototypeAttribute.
* nsIScriptGlobalObject::EnsureScriptEnvironment(PRUint32 aLangID) to
allow a global to set itself up for a new language.
git-svn-id: svn://10.0.0.236/branches/DOM_AGNOSTIC_BRANCH@180644 18797224-902f-48f8-a5cc-f745e15eee43