[webcrypto] Workaround for NSS AES-KW unwrap bug 981170

See https://bugzilla.mozilla.org/show_bug.cgi?id=981170

BUG=349939
TEST=content_unittests --gtest_filter="SharedCryptoTest*"

Review URL: https://codereview.chromium.org/190633008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256181 0039d316-1c4b-4281-b951-d872f2087c98
Define angle_revision variable in DEPS.

This will avoid duplicating ANGLE's git repo URL in the GPU recipe.

BUG=349291
TBR=jmadill@chromium.org

Review URL: https://codereview.chromium.org/193843002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256182 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256182