[webcrypto] Remove support for SHA-224 (CL 2 or 3).

Chromium side of the change.

This was removed by the spec: https://dvcs.w3.org/hg/webcrypto-api/rev/3f7df730b2c7

BUG=245025

Review URL: https://codereview.chromium.org/194203002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256764 0039d316-1c4b-4281-b951-d872f2087c98
7 files changed