remove checks not belonging in these tests

--HG--
extra : rebase_source : a056de7dd4198daaecb634840f61abbe80f30293

browser/base/content/test/tabview/browser_tabview_launch.js

@@ -44,10 +44,8 @@ function test() {
   // verify initial state
   ok(!TabView.isVisible(), "Tab View starts hidden");
 
-  // use the Tab View button to launch it for the first time
+  // launch tab view for the first time
   window.addEventListener("tabviewshown", onTabViewLoadedAndShown, false);
-  let button = document.getElementById("tabview-button");
-  ok(!button, "Tab View button not exist by default");
   let tabViewCommand = document.getElementById("Browser:ToggleTabView");
   tabViewCommand.doCommand();
 }

browser/base/content/test/tabview/browser_tabview_rtl.js

@@ -50,8 +50,6 @@ function test() {
 }
 
 function toggleTabView() {
-  let button = document.getElementById("tabview-button");
-  ok(!button, "Tab View button not exist by default");
   let tabViewCommand = document.getElementById("Browser:ToggleTabView");
   tabViewCommand.doCommand();
 }