Bug 1632249 - Mark mCapturedFrameInvalidated even if mIsCanvasDirty. r=handyman

Differential Revision: https://phabricator.services.mozilla.com/D79014

dom/canvas/WebGLContext.cpp

@@ -248,13 +248,13 @@ void WebGLContext::DestroyResourcesAndContext() {
 }
 
 void ClientWebGLContext::MarkCanvasDirty() {
-  if (mIsCanvasDirty) return;
-  mIsCanvasDirty = true;
-
   if (!mCanvasElement) return;
 
   mCapturedFrameInvalidated = true;
 
+  if (mIsCanvasDirty) return;
+  mIsCanvasDirty = true;
+
   SVGObserverUtils::InvalidateDirectRenderingObservers(mCanvasElement);
 
   mCanvasElement->InvalidateCanvasContent(nullptr);