Tweak normalization regexps to allow > in attribute values.

HTML serialization allows > in attribute values; see:
http://www.whatwg.org/specs/web-apps/current-work/multipage/the-end.html#serializing-html-fragments

And in fact we tend to get "<nowiki>" and other similar things in
attribute values.  Update the regular expressions used in
normalization to more accurately match HTML elements which may
contain quoted > in attributes.

Change-Id: I5ec8c3b79618205b7575e102a48fcd16f7479fad