Make Sec-WebSocket-Extensions parsing more strict.

RFC6455 states that unescaped quoted-string in Sec-WebSocket-Extensions
MUST conform to the 'token' ABNF in RFC2616.
We fix the parser and add unittests.

BUG=233082
R=tyoshino
TEST=webkit_unit_tests

Review URL: https://chromiumcodereview.appspot.com/17587009

git-svn-id: svn://svn.chromium.org/blink/trunk@152945 bbb929c8-8fbe-4397-9dbb-9b2b20218538