fix(router): event.defaultPrevented is not reliable (IE11)

modules/angular2/src/dom/browser_adapter.dart

@@ -135,6 +135,9 @@ class BrowserDomAdapter extends GenericBrowserDomAdapter {
   MouseEvent createMouseEvent(String eventType) =>
       new MouseEvent(eventType, canBubble: true);
   Event createEvent(String eventType) => new Event(eventType, canBubble: true);
+  void preventDefault(Event evt) { 
+    evt.preventDefault();
+  }
   String getInnerHTML(Element el) => el.innerHtml;
   String getOuterHTML(Element el) => el.outerHtml;
   void setInnerHTML(Element el, String value) {

modules/angular2/src/dom/browser_adapter.ts

@@ -77,6 +77,10 @@ createMouseEvent(eventType: string): MouseEvent {
 createEvent(eventType): Event {
   return new Event(eventType, true);
 }
+preventDefault(evt: Event) {
+  evt.preventDefault();
+  evt.returnValue = false;
+}
 getInnerHTML(el) {
   return el.innerHTML;
 }

modules/angular2/src/dom/dom_adapter.ts

@@ -33,6 +33,7 @@ export class DomAdapter {
   dispatchEvent(el, evt) { throw _abstract(); }
   createMouseEvent(eventType): any { throw _abstract(); }
   createEvent(eventType: string): any { throw _abstract(); }
+  preventDefault(evt) { throw _abstract(); }
   getInnerHTML(el): string { throw _abstract(); }
   getOuterHTML(el): string { throw _abstract(); }
   nodeName(node): string { throw _abstract(); }

modules/angular2/src/dom/html_adapter.dart

@@ -76,6 +76,9 @@ class Html5LibDomAdapter implements DomAdapter {
   createEvent(eventType) {
     throw 'not implemented';
   }
+  preventDefault(evt) { 
+    throw 'not implemented';
+  }
   getInnerHTML(el) {
     return el.innerHtml;
   }

modules/angular2/src/dom/parse5_adapter.cjs

@@ -134,6 +134,9 @@ export class Parse5DomAdapter extends DomAdapter {
       };
     return evt;
   }
+  preventDefault(evt) { 
+    evt.returnValue = false;
+  }
   getInnerHTML(el) {
     return serializer.serialize(this.templateAwareRoot(el));
   }

modules/angular2/src/router/router_link.js

@@ -54,7 +54,7 @@ export class RouterLink {
     this._location = location;
     this._params = StringMapWrapper.create();
     DOM.on(this._domEl, 'click', (evt) => {
-      evt.preventDefault();
+      DOM.preventDefault(evt);
       this._router.navigate(this._navigationHref);
     });
   }

modules/angular2/test/router/outlet_spec.js

@@ -221,7 +221,7 @@ export function main() {
             view.detectChanges();
 
             var dispatchedEvent = clickOnElement(view);
-            expect(dispatchedEvent.defaultPrevented).toBe(true);
+            expect(dispatchedEvent.defaultPrevented || !dispatchedEvent.returnValue).toBe(true);
 
             // router navigation is async.
             rtr.subscribe((_) => {
@@ -244,7 +244,7 @@ export function main() {
             view.detectChanges();
 
             var dispatchedEvent = clickOnElement(view);
-            expect(dispatchedEvent.defaultPrevented).toBe(true);
+            expect(dispatchedEvent.defaultPrevented || !dispatchedEvent.returnValue).toBe(true);
 
             // router navigation is async.
             rtr.subscribe((_) => {