Remove the VIEW_MODE_CSS_MEDIA compile-time flag.

This mechanical change should have no web-visible impact, as Chromium never
disabled the feature.

Review URL: https://chromiumcodereview.appspot.com/13902004

git-svn-id: svn://svn.chromium.org/blink/trunk@148332 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Go on a spree of CRASH -> RELEASE_ASSERT cleanup in WTF/wtf/text.

R=abarth@chromium.org
BUG=none

Review URL: https://codereview.chromium.org/13985024

git-svn-id: svn://svn.chromium.org/blink/trunk@148333 bbb929c8-8fbe-4397-9dbb-9b2b20218538