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

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 a479523b65b839aaf119d3d2608c3b175a92e870..ddfcfbf0a6de362d31c66a2918f1b0382650ff5d 100644
--- a/src/gpu/gl/GrGLUtil.cpp
+++ b/src/gpu/gl/GrGLUtil.cpp
@@ -140,7 +140,7 @@ bool GrGLIsChromiumFromRendererString(const char* rendererString) {
 GrGLVersion GrGLGetVersionFromString(const char* versionString) {
     if (NULL == versionString) {
         SkDEBUGFAIL("NULL GL version string.");
-        return 0;
+        return GR_GL_INVALID_VER;
     }
 
     int major, minor;
@@ -152,7 +152,7 @@ GrGLVersion GrGLGetVersionFromString(const char* versionString) {
         if (get_gl_version_for_mesa(mesaMajor, &major, &minor)) {
             return GR_GL_VER(major, minor);
         } else {
-            return 0;
+            return GR_GL_INVALID_VER;
         }
     }
 
@@ -173,13 +173,13 @@ GrGLVersion GrGLGetVersionFromString(const char* versionString) {
         return GR_GL_VER(major, minor);
     }
 
-    return 0;
+    return GR_GL_INVALID_VER;
 }
 
 GrGLSLVersion GrGLGetGLSLVersionFromString(const char* versionString) {
     if (NULL == versionString) {
         SkDEBUGFAIL("NULL GLSL version string.");
-        return 0;
+        return GR_GLSL_INVALID_VER;
     }
 
     int major, minor;
@@ -202,7 +202,7 @@ GrGLSLVersion GrGLGetGLSLVersionFromString(const char* versionString) {
     }
 #endif
 
-    return 0;
+    return GR_GLSL_INVALID_VER;
 }
 
 GrGLVendor GrGLGetVendorFromString(const char* vendorString) {