Updated mediawiki/extensions
Project: mediawiki/extensions/Parsoid  6aeddead96c9e78bf9b19787861cb51e9eb49774

Expose extensiontags through WikiConfig

subbu needed this functionality to check for valid extensions in the tokenizer,
and we need to expose it anyway, so here it is! Use isExtensionTag( name ) to
get a boolean.

Change-Id: I11199b26fdcf8ffe45d99d9c249e964bc4b33857