refactor(test_lib): BrowserDetection util

Closes #3805

modules/angular2/test/core/render/dom/compiler/shadow_css_spec.ts

@@ -7,7 +7,8 @@ import {
   iit,
   SpyObject,
   el,
-  normalizeCSS
+  normalizeCSS,
+  browserDetection
 } from 'angular2/test_lib';
 import {ShadowCss} from 'angular2/src/core/render/dom/compiler/shadow_css';
 
@@ -66,8 +67,7 @@ export function main() {
       });
     }
 
-    if (DOM.getUserAgent().indexOf('AppleWebKit') > -1 &&
-        DOM.getUserAgent().indexOf('Edge') == -1) {
+    if (browserDetection.isWebkit) {
       it('should handle -webkit-keyframes rules', () => {
         var css = '@-webkit-keyframes foo {0% {-webkit-transform: translate(-50%) scaleX(0);}}';
         var passRe =

modules/angular2/test/core/zone/ng_zone_spec.ts

@@ -11,9 +11,7 @@ import {
   xit,
   Log,
   isInInnerZone,
-  isAndroid,
-  isEdge,
-  isIE
+  browserDetection
 } from 'angular2/test_lib';
 
 import {PromiseCompleter, PromiseWrapper, TimerWrapper} from 'angular2/src/core/facade/async';
@@ -21,7 +19,8 @@ import {BaseException} from 'angular2/src/core/facade/lang';
 
 import {NgZone} from 'angular2/src/core/zone/ng_zone';
 
-var needsLongerTimers = isAndroid() || isEdge() || isIE();
+var needsLongerTimers =
+    browserDetection.isAndroid || browserDetection.isEdge || browserDetection.isIE;
 // Schedules a macrotask (using a timer)
 function macroTask(fn: Function, timer = 1): void {
   // adds longer timers for passing tests in IE and Edge