fix(router): Added pushState fallback for IE 9 browser.

Closes #6506

Closes #7929

modules/@angular/platform-browser/src/browser/location/browser_platform_location.ts

@@ -2,7 +2,7 @@ import {Injectable} from '@angular/core';
 import {History, Location} from '../../../src/facade/browser';
 import {UrlChangeListener, PlatformLocation} from '@angular/common';
 import {getDOM} from '../../dom/dom_adapter';
-
+import {supportsState} from './history';
 
 
 /**
@@ -46,11 +46,19 @@ export class BrowserPlatformLocation extends PlatformLocation {
   set pathname(newPath: string) { this._location.pathname = newPath; }
 
   pushState(state: any, title: string, url: string): void {
+    if(supportsState()) {
       this._history.pushState(state, title, url);
+    } else {
+      this._location.hash = url;
+    }
   }
 
   replaceState(state: any, title: string, url: string): void {
+    if(supportsState()) {
       this._history.replaceState(state, title, url);
+    } else {
+      this._location.hash = url;
+    }
   }
 
   forward(): void { this._history.forward(); }

modules/@angular/platform-browser/src/browser/location/history.dart

@@ -0,0 +1,3 @@
+import 'dart:html' show History;
+
+bool supportsState() => History.supportsState;

modules/@angular/platform-browser/src/browser/location/history.ts

@@ -0,0 +1,3 @@
+export function supportsState(): boolean {
+    return !!window.history.pushState;
+}