fix(angular.copy): support copying XML nodes

Closes #5429
Closes #12786

Author: petebacondarwin

src/Angular.js

@@ -825,6 +825,8 @@ function copy(source, destination, stackSource, stackDest) {
       } else if (isRegExp(source)) {
         destination = new RegExp(source.source, source.toString().match(/[^\/]*$/)[0]);
         destination.lastIndex = source.lastIndex;
+      } else if (isFunction(source.cloneNode)) {
+          destination = source.cloneNode(true);
       } else {
         var emptyObject = Object.create(getPrototypeOf(source));
         return copy(source, emptyObject, stackSource, stackDest);

test/AngularSpec.js

@@ -386,6 +386,18 @@ describe('angular', function() {
       expect(aCopy).toBe(aCopy.self);
     });
 
+    it('should deeply copy XML nodes', function() {
+      var anElement = document.createElement('foo');
+      anElement.appendChild(document.createElement('bar'));
+      var theCopy = anElement.cloneNode(true);
+      expect(copy(anElement).outerHTML).toEqual(theCopy.outerHTML);
+      expect(copy(anElement)).not.toBe(anElement);
+    });
+
+    it('should not try to call a non-function called `cloneNode`', function() {
+      expect(copy.bind(null, { cloneNode: 100 })).not.toThrow();
+    });
+
     it('should handle objects with multiple references', function() {
       var b = {};
       var a = [b, -1, b];