Fix decl of gl_FragCoord in GLSL versions <= 1.20.

We we're saying "in" instead of "varying".
Review URL: https://codereview.appspot.com/6779043

git-svn-id: http://skia.googlecode.com/svn/trunk@6104 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed