fix($compile): retain CSS classes added in cloneAttachFn on asynchronous directives

Previously, classes added to asynchronous directive elements during the clone
attach function would not persist after the node is merged with the template, prior
to linking. This change corrects this behaviour and brings it in line with synchronous
directives.

Closes #5439
Closes #5617

Author: caitp

src/ng/compile.js

@@ -1711,9 +1711,13 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
                 linkNode = $compileNode[0];
 
             if (beforeTemplateLinkNode !== beforeTemplateCompileNode) {
+              var oldClasses = beforeTemplateLinkNode.className;
               // it was cloned therefore we have to clone as well.
               linkNode = jqLiteClone(compileNode);
               replaceWith(linkRootElement, jqLite(beforeTemplateLinkNode), linkNode);
+
+              // Copy in CSS classes from original node
+              safeAddClass(jqLite(linkNode), oldClasses);
             }
             if (afterTemplateNodeLinkFn.transclude) {
               childBoundTranscludeFn = createBoundTranscludeFn(scope, afterTemplateNodeLinkFn.transclude);

test/ng/compileSpec.js

@@ -1128,6 +1128,26 @@ describe('$compile', function() {
         });
 
 
+        it('should copy classes from pre-template node into linked element', function() {
+          module(function() {
+            directive('test', valueFn({
+              templateUrl: 'test.html',
+              replace: true
+            }));
+          });
+          inject(function($compile, $templateCache, $rootScope) {
+            var child;
+            $templateCache.put('test.html', '<p class="template-class">Hello</p>');
+            element = $compile('<div test></div>')($rootScope, function(node) {
+              node.addClass('clonefn-class');
+            });
+            $rootScope.$digest();
+            expect(element).toHaveClass('template-class');
+            expect(element).toHaveClass('clonefn-class');
+          });
+        });
+
+
         describe('delay compile / linking functions until after template is resolved', function(){
           var template;
           beforeEach(module(function() {