Bug 1973975 - Ensure that glMakeCurrent is called when rendering without presenting. r=gfx-reviewers,aosmond a=pascalc

Differential Revision: https://phabricator.services.mozilla.com/D255987

gfx/webrender_bindings/RendererOGL.cpp

@@ -205,6 +205,9 @@ RenderedFrameId RendererOGL::UpdateAndRender(
          layers::ProfilerScreenshots::IsEnabled())) {
       fullRender = true;
     }
+  } else if (!mCompositor->MakeCurrent()) {
+    // MakeCurrent is otherwise called by mCompositor->BeginFrame above.
+    return RenderedFrameId();
   }
 
   if (!beginFrame) {