fix(register-element): add check for callback being own property of opts

Using other component libraries, like Polymer, alongside Angular2+zones would
cause errors because the descriptor was undefined after calling getOwnPropertyDescriptor
on objects which had inherited callbacks that were not their own properties.

Fixes #52

lib/patch/register-element.js

@@ -16,15 +16,22 @@ function apply() {
   ];
 
   document.registerElement = function (name, opts) {
-    callbacks.forEach(function (callback) {
-      if (opts.prototype[callback]) {
-        var descriptor = Object.getOwnPropertyDescriptor(opts.prototype, callback);
-        if (descriptor.value) {
-          descriptor.value = global.zone.bind(descriptor.value || opts.prototype[callback]);
-          _redefineProperty(opts.prototype, callback, descriptor);
+    if (opts && opts.prototype) {
+      callbacks.forEach(function (callback) {
+        if (opts.prototype.hasOwnProperty(callback)) {
+          var descriptor = Object.getOwnPropertyDescriptor(opts.prototype, callback);
+          if (descriptor.value) {
+            descriptor.value = global.zone.bind(descriptor.value);
+            _redefineProperty(opts.prototype, callback, descriptor);
+          } else {
+            opts.prototype[callback] = global.zone.bind(opts.prototype[callback]);
+          }
+        } else if (opts.prototype[callback]) {
+          opts.prototype[callback] = global.zone.bind(opts.prototype[callback]);
         }
-      }
-    });
+      });
+    }
+
     return _registerElement.apply(document, [name, opts]);
   };
 }

test/patch/registerElement.spec.js

@@ -129,4 +129,33 @@ describe('document.registerElement', ifEnvSupports(registerElement, function ()
     var elt = document.createElement('x-props-desc');
   });
 
+
+  it('should check bind callback if not own property', function (done) {
+    testZone.run(function() {
+      var originalProto = {
+        createdCallback: checkZone
+      };
+
+      var secondaryProto = Object.create(originalProto);
+      expect(secondaryProto.createdCallback).toBe(originalProto.createdCallback);
+
+      document.registerElement('x-inherited-callback', { prototype: secondaryProto });
+      expect(secondaryProto.createdCallback).not.toBe(originalProto.createdCallback);
+
+      function checkZone() {
+        expect(window.zone).toBeDirectChildOf(testZone);
+        done();
+      }
+
+      var elt = document.createElement('x-inherited-callback');
+    });
+  });
+
+
+  it('should not throw if no options passed to registerElement', function () {
+    expect(function() {
+      document.registerElement('x-no-opts');
+    }).not.toThrow();
+  });
+
 }));