Rename kES2_GrGLBinding to kES_GrGLBinding. Step 0 for supporting ES3.

src/gpu/gl/GrGLUtil.cpp

Index: src/gpu/gl/GrGLUtil.cpp
diff --git a/src/gpu/gl/GrGLUtil.cpp b/src/gpu/gl/GrGLUtil.cpp
index a13b03de77577166f5e231b53e15bd08d15fe562..0c1434807b6878da91c16885e8629272a421e004 100644
--- a/src/gpu/gl/GrGLUtil.cpp
+++ b/src/gpu/gl/GrGLUtil.cpp
@@ -116,7 +116,7 @@ GrGLBinding GrGLGetBindingInUseFromString(const char* versionString) {
     // check for ES2
     n = sscanf(versionString, "OpenGL ES %d.%d", &major, &minor);
     if (2 == n) {
-        return kES2_GrGLBinding;
+        return kES_GrGLBinding;
     }
     return kNone_GrGLBinding;
 }