<a href="Foo%3F"> would dirty-diff to <a href="Foo?"> and also render
as such, pointing to the wrong page.
We also called decodeURIComponent() on the href twice, which can't
have been good.
Move URI decoding and underscore normalization into
getTargetDataFromHref(), and add rawTitle for callers that need it.
Put rawTitle in the origTitle attribute, so that equivalence
comparisons (decode(origTitle) === title) work as intended.
Bug: T145978
Change-Id: I29331a4ab0f8f7ef059c109f6813fa670a2c7390
