make xhr.cache optionally synchronous

- add `sync` flag xhr.cache
- change ng:include to use the sync flag
- change ng:view to use the sync flag

The end result is that there are fewer repaints in the browser,
which means less "blinking" that user sees.

src/service/xhr.cache.js

@@ -20,18 +20,25 @@
  * @param {boolean=} [verifyCache=false] If `true` then a result is immediately returned from cache
  *   (if present) while a request is sent to the server for a fresh response that will update the
  *   cached entry. The `callback` function will be called when the response is received.
+ * @param {boolean=} [sync=false] in case of cache hit execute `callback` synchronously.
  */
 angularServiceInject('$xhr.cache', function($xhr, $defer, $log){
   var inflight = {}, self = this;
-  function cache(method, url, post, callback, verifyCache){
+  function cache(method, url, post, callback, verifyCache, sync){
     if (isFunction(post)) {
       callback = post;
       post = null;
     }
     if (method == 'GET') {
       var data, dataCached;
       if (dataCached = cache.data[url]) {
-        $defer(function() { callback(200, copy(dataCached.value)); });
+
+        if (sync) {
+          callback(200, copy(dataCached.value));
+        } else {
+          $defer(function() { callback(200, copy(dataCached.value)); });
+        }
+
         if (!verifyCache)
           return;
       }

src/widgets.js

@@ -673,12 +673,12 @@ angularWidget('ng:include', function(element){
             useScope = this.$eval(scopeExp);
 
         if (src) {
-          xhr('GET', src, function(code, response){
+          xhr('GET', src, null, function(code, response){
             element.html(response);
             childScope = useScope || createScope(scope);
             compiler.compile(element)(childScope);
             scope.$eval(onloadExp);
-          });
+          }, false, true);
         } else {
           childScope = null;
           element.html('');
@@ -1066,10 +1066,10 @@ angularWidget('ng:view', function(element) {
         }
 
         if (src) {
-          $xhr('GET', src, function(code, response){
+          $xhr('GET', src, null, function(code, response){
             element.html(response);
             compiler.compile(element)(childScope);
-          });
+          }, false, true);
         } else {
           element.html('');
         }

test/service/xhr.cacheSpec.js

@@ -107,6 +107,22 @@ describe('$xhr.cache', function() {
   });
 
 
+  it('should call callback synchronously when sync flag is on', function() {
+    $browserXhr.expectGET('/url').respond('+');
+    cache('GET', '/url', null, callback, false, true);
+    expect(log).toEqual(''); //callback hasn't executed
+
+    $browserXhr.flush();
+    expect(log).toEqual('"+";'); //callback has executed
+
+    cache('GET', '/url', null, callback, false, true);
+    expect(log).toEqual('"+";"+";'); //callback has executed
+
+    $browser.defer.flush();
+    expect(log).toEqual('"+";"+";'); //callback was not called again any more
+  });
+
+
   it('should call eval after callbacks for both cache hit and cache miss execute', function() {
     var eval = this.spyOn(scope, '$eval').andCallThrough();
 

test/widgetsSpec.js

@@ -610,7 +610,6 @@ describe("widget", function(){
       scope.url = 'myUrl';
       scope.$service('$xhr.cache').data.myUrl = {value:'{{name}}'};
       scope.$eval();
-      scope.$service('$browser').defer.flush();
       expect(element.text()).toEqual('misko');
       dealoc(scope);
     });
@@ -623,7 +622,6 @@ describe("widget", function(){
       scope.url = 'myUrl';
       scope.$service('$xhr.cache').data.myUrl = {value:'{{name}}'};
       scope.$eval();
-      scope.$service('$browser').defer.flush();
 
       expect(element.text()).toEqual('igor');
 
@@ -640,7 +638,6 @@ describe("widget", function(){
       scope.url = 'myUrl';
       scope.$service('$xhr.cache').data.myUrl = {value:'{{c=c+1}}'};
       scope.$eval();
-      scope.$service('$browser').defer.flush();
 
       // this one should really be just '1', but due to lack of real events things are not working
       // properly. see discussion at: http://is.gd/ighKk
@@ -657,7 +654,6 @@ describe("widget", function(){
       scope.url = 'myUrl';
       scope.$service('$xhr.cache').data.myUrl = {value:'my partial'};
       scope.$eval();
-      scope.$service('$browser').defer.flush();
       expect(element.text()).toEqual('my partial');
       expect(scope.loaded).toBe(true);
       dealoc(element);