xmlDocPtrForString shouldn't use bloatedCharacters()
xmlDocPtrForString shouldn't use bloatedCharacters()

libxml can handle different encodings. We don't need to upconvert to UTF-16
just to pass the data to libxml.

R=pdr
BUG=254708

Review URL: https://chromiumcodereview.appspot.com/18223008

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@153276 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs