Fail to create GrContext when we get a NULL for a GL/GLSL version string

src/gpu/gl/GrGLUtil.h

Index: src/gpu/gl/GrGLUtil.h
diff --git a/src/gpu/gl/GrGLUtil.h b/src/gpu/gl/GrGLUtil.h
index b99487a1af6a7a2b680c3d0b1e868ec4f176dea1..73fcec1177011f0220007a97a53138bea226881a 100644
--- a/src/gpu/gl/GrGLUtil.h
+++ b/src/gpu/gl/GrGLUtil.h
@@ -18,6 +18,14 @@ class SkMatrix;
 typedef uint32_t GrGLVersion;
 typedef uint32_t GrGLSLVersion;
 
+#define GR_GL_VER(major, minor) ((static_cast<int>(major) << 16) | \
+                                 static_cast<int>(minor))
+#define GR_GLSL_VER(major, minor) ((static_cast<int>(major) << 16) | \
+                                   static_cast<int>(minor))
+
+#define GR_GL_INVALID_VER GR_GL_VER(0, 0)
+#define GR_GLSL_INVALID_VER GR_GL_VER(0, 0)
+
 /**
  * The Vendor and Renderer enum values are lazily updated as required.
  */
@@ -37,11 +45,6 @@ enum GrGLRenderer {
     kOther_GrGLRenderer
 };
 
-#define GR_GL_VER(major, minor) ((static_cast<int>(major) << 16) | \
-                                 static_cast<int>(minor))
-#define GR_GLSL_VER(major, minor) ((static_cast<int>(major) << 16) | \
-                                   static_cast<int>(minor))
-
 ////////////////////////////////////////////////////////////////////////////////
 
 /**