Update scheme list according to latest specification

New schemes are added to it additionally. Those are im, ircs and webtai.

Spec: http://www.w3.org/html/wg/drafts/html/master/webappapis.html#custom-handlers

As additional work, scheme order is listed to be sync with spec.

TESTS=fast/dom/register-protocol-handler.html
fast/dom/unregister-protocol-handler.html

BUG=

Review URL: https://chromiumcodereview.appspot.com/21714004

git-svn-id: svn://svn.chromium.org/blink/trunk@155491 bbb929c8-8fbe-4397-9dbb-9b2b20218538