--- a/widget/tests/bug586713_window.xul
+++ b/widget/tests/bug586713_window.xul
@@ -39,12 +39,12 @@
       if (fooCallCount == 2) {
         ok(true, "If we got here we didn't crash, excellent.");
         onTestsFinished();
       }
     }
 
     function onLoad() {
       foo();
-      setTimeout(function() foo(), 0);
+      setTimeout(() => foo(), 0);
     }
   ]]></script>
 </window>

--- a/widget/tests/test_bug760802.xul
+++ b/widget/tests/test_bug760802.xul
@@ -46,17 +46,19 @@ function shouldThrowException(fun, excep
     fun.call();
     return false;
   } catch (e) {
     $("display").innerHTML += "<br/>OK thrown: "+e.message;
     return (e instanceof Components.Exception &&
             e.result === exception)
   }
 }
-function doesntThrowException(fun) !shouldThrowException(fun)
+function doesntThrowException(fun) {
+  return !shouldThrowException(fun);
+}
 
 var baseWindow = getBaseWindowInterface(this);
 var nativeHandle = baseWindow.nativeHandle;
 $("display").innerHTML = "found nativeHandle for this window: "+nativeHandle;
 
 var wm = Cc["@mozilla.org/appshell/window-mediator;1"].getService(Ci.nsIWindowMediator);
 var win = wm.getMostRecentWindow("navigator:browser");
 var docShell = getBaseWindowInterfaceFromDocShell(win);

--- a/widget/tests/test_taskbar_progress.xul
+++ b/widget/tests/test_taskbar_progress.xul
@@ -62,17 +62,19 @@
         try {
           progress.setProgressState(s,c,m);
           return false;
         } catch (e) {
           return true;
         }
       }
 
-      function doesntThrow(s,c,m) !shouldThrow(s,c,m)
+      function doesntThrow(s,c,m) {
+        return !shouldThrow(s,c,m);
+      }
 
       ok(doesntThrow(TP.STATE_NO_PROGRESS, 0, 0), "No progress state can be set");
       ok(doesntThrow(TP.STATE_INDETERMINATE, 0, 0), "Indeterminate state can be set");
       ok(doesntThrow(TP.STATE_NORMAL, 0, 0), "Normal state can be set");
       ok(doesntThrow(TP.STATE_ERROR, 0, 0), "Error state can be set");
       ok(doesntThrow(TP.STATE_PAUSED, 0, 0), "Paused state can be set");
 
       ok(shouldThrow(TP.STATE_NO_PROGRESS, 1, 1), "Cannot set no progress with values");