Bug 1562622 - Calling getViewTreeObserver again to get new object to test isAlive().;r=VladBaicu

Differential Revision: https://phabricator.services.mozilla.com/D39929

--HG--
extra : moz-landing-system : lando

mobile/android/base/java/org/mozilla/gecko/home/TabMenuStripLayout.java

@@ -129,6 +129,7 @@ class TabMenuStripLayout extends ThemedLinearLayout
             vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                 @Override
                 public void onGlobalLayout() {
+                    ViewTreeObserver vto = getViewTreeObserver();
                     if (!vto.isAlive()) {
                         return;
                     }