fix(a): workaround IE bug affecting mailto urls

Apparently there is a really weird bug in IE6-8 that causes anchor textContent
to be reset with href content when both contain @ symbol.

Inserting a bogus comment node into all anchor elements in IE works around this
browser bug.

I'm fixing the issue via directive because that way we'll fix it for jQuery as
well.

I fixed an e2e test too because it was incorrect.

Closes #1949

src/ng/directive/a.js

@@ -16,10 +16,20 @@
 var htmlAnchorDirective = valueFn({
   restrict: 'E',
   compile: function(element, attr) {
-    // turn <a href ng-click="..">link</a> into a link in IE
-    // but only if it doesn't have name attribute, in which case it's an anchor
-    if (!attr.href) {
-      attr.$set('href', '');
+
+    if (msie <= 8) {
+
+      // turn <a href ng-click="..">link</a> into a stylable link in IE
+      // but only if it doesn't have name attribute, in which case it's an anchor
+      if (!attr.href && !attr.name) {
+        attr.$set('href', '');
+      }
+
+      // add a comment node to anchors to workaround IE bug that causes element content to be reset
+      // to new attribute content if attribute is updated with value containing @ and element also
+      // contains value with @
+      // see issue #1949
+      element.append(document.createComment('IE fix'));
     }
 
     return function(scope, element) {

src/ng/directive/booleanAttrs.js

@@ -66,7 +66,7 @@
         it('should execute ng-click but not reload when no href but name specified', function() {
           element('#link-5').click();
           expect(input('value').val()).toEqual('5');
-          expect(element('#link-5').attr('href')).toBe('');
+          expect(element('#link-5').attr('href')).toBe(undefined);
         });
 
         it('should only change url when only ng-href', function() {