Skia no longer uses fMinSampleShading, so remove function pointer init

See also https://skia-review.googlesource.com/c/skia/+/175423

Change-Id: Ieb8afcaa232cbf5aef78a28823e7f7528e048153
Reviewed-on: https://chromium-review.googlesource.com/c/1366758Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Cr-Commit-Position: refs/heads/master@{#614824}

ui/gl/init/create_gr_gl_interface.cc

@@ -523,9 +523,6 @@ sk_sp<GrGLInterface> CreateGrGLInterface(
   // functions->fCreateImage = nullptr;
   // functions->fDestroyImage = nullptr;
 
-  // GL 4.0 or GL_ARB_sample_shading or ES+GL_OES_sample_shading
-  functions->fMinSampleShading = gl->glMinSampleShadingFn;
-
   functions->fFenceSync = gl->glFenceSyncFn;
   functions->fIsSync = gl->glIsSyncFn;
   functions->fClientWaitSync = gl->glClientWaitSyncFn;