Use deferred style recalc for xml/xsl.

There should be no need to do synchronous style recalcs when finishing XML
parsing, regardless of the presence of XSL stylesheets.

BUG=374162

Review URL: https://codereview.chromium.org/292743002

git-svn-id: svn://svn.chromium.org/blink/trunk@174343 bbb929c8-8fbe-4397-9dbb-9b2b20218538