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

src/gpu/gl/GrGLExtensions.cpp

Index: src/gpu/gl/GrGLExtensions.cpp
diff --git a/src/gpu/gl/GrGLExtensions.cpp b/src/gpu/gl/GrGLExtensions.cpp
index 6d1b04d2cc6ced84e7f01420bf5f95f28302110e..53013df64da1e4974fb073f4e66d6016ff793e3f 100644
--- a/src/gpu/gl/GrGLExtensions.cpp
+++ b/src/gpu/gl/GrGLExtensions.cpp
@@ -54,10 +54,11 @@ bool GrGLExtensions::init(GrGLStandard standard,
 
     // glGetStringi and indexed extensions were added in version 3.0 of desktop GL and ES.
     const GrGLubyte* verString = getString(GR_GL_VERSION);
-    if (NULL == verString) {
+    GrGLVersion version = GrGLGetVersionFromString((const char*) verString);
+    if (GR_GL_INVALID_VER == version) {
         return false;
     }
-    GrGLVersion version = GrGLGetVersionFromString((const char*) verString);
+
     bool indexed = version >= GR_GL_VER(3, 0);
 
     if (indexed) {