fix($rootScope): remove history event handler when app is torn down

Remember the popstate and hashchange handler registered with window
when the application bootstraps, and remove it when the application
is torn down

Closes angular#9897

src/ng/browser.js

@@ -222,10 +222,16 @@ function Browser(window, document, $log, $sniffer) {
   var urlChangeListeners = [],
       urlChangeInit = false;
 
-  function cacheStateAndFireUrlChange() {
+  /**
+   * @private
+   * Event handler for hashchange and popstate events.
+   * Note: this method is used only by $rootScope to remove the handler when an app
+   *       is torn down. (See https://github.com/angular/angular.js/issues/9897)
+   */
+  self.cacheStateAndFireUrlChange = function() {
     cacheState();
     fireUrlChange();
-  }
+  };
 
   // This variable should be used *only* inside the cacheState function.
   var lastCachedState = null;
@@ -282,9 +288,9 @@ function Browser(window, document, $log, $sniffer) {
       // changed by push/replaceState
 
       // html5 history api - popstate event
-      if ($sniffer.history) jqLite(window).on('popstate', cacheStateAndFireUrlChange);
+      if ($sniffer.history) jqLite(window).on('popstate', self.cacheStateAndFireUrlChange);
       // hashchange event
-      jqLite(window).on('hashchange', cacheStateAndFireUrlChange);
+      jqLite(window).on('hashchange', self.cacheStateAndFireUrlChange);
 
       urlChangeInit = true;
     }

src/ng/rootScope.js

@@ -861,7 +861,14 @@ function $RootScopeProvider() {
 
         this.$broadcast('$destroy');
         this.$$destroyed = true;
-        if (this === $rootScope) return;
+
+        if (this === $rootScope) {
+          //Remove handlers attached to window when $rootScope is removed
+          //See https://github.com/angular/angular.js/issues/9897
+          jqLite(window).unbind("popstate", $browser.cacheStateAndFireUrlChange);
+          jqLite(window).unbind("hashchange", $browser.cacheStateAndFireUrlChange);
+          return;
+        }
 
         for (var eventName in this.$$listenerCount) {
           decrementListenerCount(this, this.$$listenerCount[eventName], eventName);