Remove all uses of the ASCIILiteral class.

This class doesn't do anything anymore.

R=abarth@chromium.org

Review URL: https://chromiumcodereview.appspot.com/22572005

git-svn-id: svn://svn.chromium.org/blink/trunk@155917 bbb929c8-8fbe-4397-9dbb-9b2b20218538