Originally we only match varying variables in vertex/fragment shaders.  However, we should also match uniform names.  For example, if a uniform variable name is used in both vertex and fragment shader, and after mapping the names are different, then the name mapping table is no longer 1:1.

BUG=106638 (crbug)
TEST=http://seanseefried.com/chrome-bug/simple-broken.html shows a magenta square
Review URL: http://codereview.appspot.com/5520051

git-svn-id: https://angleproject.googlecode.com/svn/trunk@939 736b8ea6-26fd-11df-bfd4-992fa37f6226