Add more globals to whitelist for safari

Fixes #3199

package.json

@@ -17,7 +17,7 @@
     "lazypipe": "^0.2.3",
     "polyclean": "^1.2.0",
     "run-sequence": "^1.1.0",
-    "web-component-tester": "^3.3.21"
+    "web-component-tester": "^4"
   },
   "scripts": {
     "build": "gulp",

test/unit/globals.html

@@ -40,6 +40,11 @@ suite('globals', function() {
     // Polymer
     Polymer: true,
     currentImport: true
+
+    // weird safari + selenium globals
+    alert: true,
+    confirm: true,
+    prompt: true
   };
 
   test('check global leakage', function() {