fix(paramTypes.hash): Update hash for each transition

The hash parameter (`#`) is now a `dynamic: true` param, and equals are compared with coersion, such that "" == undefined == null.
Closes #2742

src/params/paramTypes.ts

@@ -23,7 +23,7 @@ export class ParamTypes {
       decode: valFromString,
       is: is(String),
       pattern: /.*/,
-      equals: val(true)
+      equals: (a, b) => a == b // allow coersion for null/undefined/""
     },
     "string": {
       encode: valToString,

src/state/stateRegistry.ts

@@ -27,7 +27,7 @@ export class StateRegistry {
       url: '^',
       views: null,
       params: {
-        '#': { value: null, type: 'hash' }
+        '#': { value: null, type: 'hash', dynamic: true }
       },
       abstract: true
     };

test/ng1/stateSpec.js

@@ -663,6 +663,21 @@ describe('state', function () {
       expect($location.hash()).toBe('frag');
     }));
 
+    it('runs a transition when the location #fragment is updated', inject(function ($state, $q, $location, $transitions) {
+      var transitionCount = 0;
+      $transitions.onSuccess({}, function() { transitionCount++; });
+
+      $state.transitionTo('home.item', {id: 'world', '#': 'frag'});
+      $q.flush();
+      expect($location.hash()).toBe('frag');
+      expect(transitionCount).toBe(1);
+
+      $state.transitionTo('home.item', {id: 'world', '#': 'blarg'});
+      $q.flush();
+      expect($location.hash()).toBe('blarg');
+      expect(transitionCount).toBe(2);
+    }));
+
     it('injects $transition$ into resolves', inject(function ($state, $q) {
       $state.transitionTo('home'); $q.flush();
       $state.transitionTo('about'); $q.flush();