Clean up MediaQueryExp parsing logic
Clean up MediaQueryExp parsing logic

This patch cleans up the parsing logic in MediaQueryExp. One notable
change here is that we now check a tokens type for NumberToken instead
of its unitType for CSS_NUMBER, which would have been an uninitialized
memory read.

BUG=508705

Review URL: https://codereview.chromium.org/1235783004

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@199000 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk,Pluto-tv/blink-crosswalk