Add validation check that linewidth func is present (we already call it on ES).

src/gpu/gl/GrGLInterface.cpp

Index: src/gpu/gl/GrGLInterface.cpp
===================================================================
--- src/gpu/gl/GrGLInterface.cpp	(revision 10811)
+++ src/gpu/gl/GrGLInterface.cpp	(working copy)
@@ -90,6 +90,7 @@
         NULL == fGetString ||
         NULL == fGetUniformLocation ||
         NULL == fLinkProgram ||
+        NULL == fLineWidth ||
         NULL == fPixelStorei ||
         NULL == fReadPixels ||
         NULL == fScissor ||
@@ -273,8 +274,7 @@
 
     // part of desktop GL, but not ES
     if (kDesktop_GrGLBinding == binding &&
-        (NULL == fLineWidth ||
-         NULL == fGetTexLevelParameteriv ||
+        (NULL == fGetTexLevelParameteriv ||
          NULL == fDrawBuffer ||
          NULL == fReadBuffer)) {
         return false;