fix($compile): do not merge attrs that are the same for replace directives

If a directives specifies `replace:true` and the template of the directive contains
a root element with an attribute which already exists at the place
where the directive is used with the same value, don't duplicate the value.

Closes #7463

src/ng/compile.js

@@ -1631,7 +1631,7 @@ function $CompileProvider($provide, $$sanitizeUriProvider) {
       // reapply the old attributes to the new element
       forEach(dst, function(value, key) {
         if (key.charAt(0) != '$') {
-          if (src[key]) {
+          if (src[key] && src[key] !== value) {
             value += (key === 'style' ? ';' : ' ') + src[key];
           }
           dst.$set(key, value, true, srcAttr[key]);

test/ng/compileSpec.js

@@ -493,6 +493,15 @@ describe('$compile', function() {
               expect(element).toBe(attr.$$element);
             }
           }));
+          directive('nomerge', valueFn({
+            restrict: 'CAM',
+            replace: true,
+            template: '<div class="log" id="myid" high-log>No Merge!</div>',
+            compile: function(element, attr) {
+              attr.$set('compiled', 'COMPILED');
+              expect(element).toBe(attr.$$element);
+            }
+          }));
           directive('append', valueFn({
             restrict: 'CAM',
             template: '<div class="log" style="width: 10px" high-log>Append!</div>',
@@ -597,6 +606,16 @@ describe('$compile', function() {
           expect(div.attr('high-log')).toEqual('');
         }));
 
+        it('should not merge attributes if they are the same', inject(function($compile, $rootScope) {
+          element = $compile(
+            '<div><div nomerge class="medium-log" id="myid"></div><div>')
+            ($rootScope);
+          var div = element.find('div');
+          expect(div.hasClass('medium-log')).toBe(true);
+          expect(div.hasClass('log')).toBe(true);
+          expect(div.attr('id')).toEqual('myid');
+        }));
+
         it('should prevent multiple templates per element', inject(function($compile) {
           try {
             $compile('<div><span replace class="replace"></span></div>');