Handled case where selection nodes that use ternary operators are part of a sequence. Usually they are part of an assignment. BUG=4 TEST=OpenGL ES 2.0 conformance tests, specifically operators test. Review URL: http://codereview.appspot.com/1643043 git-svn-id: https://angleproject.googlecode.com/svn/trunk@335 736b8ea6-26fd-11df-bfd4-992fa37f6226