Bug 1437949 - Follow-up to make the GL context current before poking the WR renderer. r=sotaro

MozReview-Commit-ID: DIpnRZcGb3Q

gfx/webrender_bindings/RendererOGL.cpp

@@ -84,7 +84,9 @@ RendererOGL::GetExternalImageHandler()
 void
 RendererOGL::Update()
 {
-  wr_renderer_update(mRenderer);
+  if (gl()->MakeCurrent()) {
+    wr_renderer_update(mRenderer);
+  }
 }
 
 bool