Upstream various build fixes from WebKit to ANGLE to make updating ANGLE in WebKit easier.

a) http://trac.webkit.org/changeset/127747
b) http://trac.webkit.org/changeset/128539
c) http://trac.webkit.org/changeset/122870 - Specifically, items #3 and #4 in this changeset's commit message.

Review URL: https://codereview.appspot.com/7040045


git-svn-id: http://angleproject.googlecode.com/svn/trunk@1640 736b8ea6-26fd-11df-bfd4-992fa37f6226