No-default properties are now expressed as undefined on publish, not as empty objects

Author: Scott J. Miles

test/html/publish-attributes.html

@@ -54,19 +54,21 @@
   <script>
       var assert = chai.assert;
       document.addEventListener('polymer-ready', function() {
+        
         // tests publishAttributes
+        
         assert.deepEqual(
             XFoo.prototype.publish, 
-            {Foo: {}, baz: {}}, 1);
+            {Foo: undefined, baz: undefined}, 1);
         assert.deepEqual(
             XBar.prototype.publish, 
-            {Foo: {}, baz: {}, Bar: {}}, 2);
+            {Foo: undefined, baz: undefined, Bar: undefined}, 2);
         assert.deepEqual(
             XZot.prototype.publish, 
-            {Foo: {}, baz: {}, Bar: {}, zot: 3}, 3);
+            {Foo: undefined, baz: undefined, Bar: undefined, zot: 3}, 3);
         assert.deepEqual(
             XSquid.prototype.publish, 
-            {Foo: {}, baz: 13, Bar: {}, zot: 5, squid: 7}, 4);
+            {Foo: undefined, baz: 13, Bar: undefined, zot: 5, squid: 7}, 4);
 
         // tests publishProperties