fix(jqLite): silently ignore after() if element has no parent

Previously, the element was always assumed to have a parent and an error was
thrown when that was not the case.
This commit makes jqLite consistent with jQuery, which silently ignores a call
on elements that do not have a parent.

Fixes #15331
Closes #15367

Closes #15475

Author: gkalpak

src/jqLite.js

@@ -979,12 +979,15 @@ forEach({
 
   after: function(element, newElement) {
     var index = element, parent = element.parentNode;
-    newElement = new JQLite(newElement);
 
-    for (var i = 0, ii = newElement.length; i < ii; i++) {
-      var node = newElement[i];
-      parent.insertBefore(node, index.nextSibling);
-      index = node;
+    if (parent) {
+      newElement = new JQLite(newElement);
+
+      for (var i = 0, ii = newElement.length; i < ii; i++) {
+        var node = newElement[i];
+        parent.insertBefore(node, index.nextSibling);
+        index = node;
+      }
     }
   },
 

test/jqLiteSpec.js

@@ -2182,6 +2182,14 @@ describe('jqLite', function() {
       span.after('abc');
       expect(root.html().toLowerCase()).toEqual('<span></span>abc');
     });
+
+
+    it('should not throw when the element has no parent', function() {
+      var span = jqLite('<span></span>');
+      expect(function() { span.after('abc'); }).not.toThrow();
+      expect(span.length).toBe(1);
+      expect(span[0].outerHTML).toBe('<span></span>');
+    });
   });