Rename kES2_GrGLBinding to kES_GrGLBinding. Step 0 for supporting ES3.

R=robertphillips@google.com

Review URL: https://codereview.chromium.org/23185004

git-svn-id: http://skia.googlecode.com/svn/trunk@10747 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGLUtil.cpp b/src/gpu/gl/GrGLUtil.cpp
index a13b03d..0c14348 100644
--- a/src/gpu/gl/GrGLUtil.cpp
+++ b/src/gpu/gl/GrGLUtil.cpp
@@ -116,7 +116,7 @@
     // check for ES2
     n = sscanf(versionString, "OpenGL ES %d.%d", &major, &minor);
     if (2 == n) {
-        return kES2_GrGLBinding;
+        return kES_GrGLBinding;
     }
     return kNone_GrGLBinding;
 }