Bug 1742797 - Fix intermittent test failures, r=hiro.

Differential Revision: https://phabricator.services.mozilla.com/D151480

browser/base/content/test/performance/browser_panel_vsync.js

@@ -38,16 +38,12 @@ add_task(
       DownloadsPanel.panel,
       "popuphidden"
     );
-    EventUtils.synthesizeNativeMouseEvent({
-      type: "click",
-      target: downloadsButton,
-      atCenter: true,
-    });
-
-    await Promise.all([
-      hiddenPromise,
-      TestUtils.waitForCondition(() => !ChromeUtils.vsyncEnabled()),
-    ]);
+    EventUtils.synthesizeKey("VK_ESCAPE", {}, window);
+    await hiddenPromise;
+    await TestUtils.waitForCondition(
+      () => !ChromeUtils.vsyncEnabled(),
+      "wait for vsync to be disabled again"
+    );
 
     ok(!ChromeUtils.vsyncEnabled(), "vsync should still be off");
     is(

layout/xul/nsMenuPopupFrame.cpp

@@ -1099,7 +1099,7 @@ void nsMenuPopupFrame::HidePopup(bool aDeselectMenu, nsPopupState aNewState) {
   mHFlip = mVFlip = false;
 
   if (auto* widget = GetWidget()) {
-    widget->ClearCachedWebrenderResources();
+    widget->ClearWebrenderAnimationResources();
   }
 
   nsView* view = GetView();