Add support for glCompressedTexSubImage2D

src/gpu/gl/GrGLInterface.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "gl/GrGLInterface.h"
 #include "gl/GrGLExtensions.h"
@@ skipping 339 matching lines @@
                 NULL == fFunctions.fPointAlongPath) {
                 RETURN_FALSE_INTERFACE
             }
         }
     }
 
     // optional function on desktop before 1.3
     if (kGL_GrGLStandard != fStandard ||
         (glVer >= GR_GL_VER(1,3)) ||
         fExtensions.has("GL_ARB_texture_compression")) {
-        if (NULL == fFunctions.fCompressedTexImage2D) {
+        if (NULL == fFunctions.fCompressedTexImage2D ||
+            NULL == fFunctions.fCompressedTexSubImage2D) {
             RETURN_FALSE_INTERFACE
         }
     }
 
     // part of desktop GL, but not ES
     if (kGL_GrGLStandard == fStandard &&
         (NULL == fFunctions.fGetTexLevelParameteriv ||
          NULL == fFunctions.fDrawBuffer ||
          NULL == fFunctions.fReadBuffer)) {
         RETURN_FALSE_INTERFACE
@@ skipping 146 matching lines @@
     if (glVer >= GR_GL_VER(3,0) ||
         (kGLES_GrGLStandard == fStandard && fExtensions.has("GL_EXT_map_buffer_range")) ||
         (kGL_GrGLStandard == fStandard && fExtensions.has("GL_ARB_map_buffer_range"))) {
         if (NULL == fFunctions.fMapBufferRange ||
             NULL == fFunctions.fFlushMappedBufferRange) {
             RETURN_FALSE_INTERFACE;
         }
     }
     return true;
 }