Added parentheses around a few operators so that if they are used in a compound statement, order of operations is preserved.
BUG=5
TEST=OpenGL ES 2.0 conformance tests.
Review URL: http://codereview.appspot.com/1691041

git-svn-id: https://angleproject.googlecode.com/svn/trunk@336 736b8ea6-26fd-11df-bfd4-992fa37f6226