Expand WidthCache for complex text width queries

Expand use of WidthCache to apply to all complex text width queries.
It'll still bail out for queries where the GlyphOverflow bounds are
needed.

BUG=347186
R=dominik.rottsches@intel.com

Review URL: https://codereview.chromium.org/206793005

git-svn-id: svn://svn.chromium.org/blink/trunk@169800 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Renamed MediaQueryExp::create

Since MediaQueryExp::create returns a nullptr when the input string is not a valid media feature,
I've renamed it to createIfValid.

BUG=

Review URL: https://codereview.chromium.org/209443002

git-svn-id: svn://svn.chromium.org/blink/trunk@169801 bbb929c8-8fbe-4397-9dbb-9b2b20218538