Enable opt-in attribute reflection via publish block.

e.g.

publish: {
  foo: {value: 'bar', reflect: true}
}

src/declaration/properties.js

@@ -97,9 +97,7 @@
       var n$ = prototype._publishNames;
       if (n$ && n$.length) {
         for (var i=0, l=n$.length, n, fn; (i<l) && (n=n$[i]); i++) {
-          fn = prototype.reflect[n] ? prototype.reflectPropertyToAttribute :
-              null;
-          Observer.createBindablePrototypeAccessor(prototype, n, fn);
+          Observer.createBindablePrototypeAccessor(prototype, n);
         }
       }
     }

src/instance/properties.js

@@ -58,6 +58,11 @@
         }
       }
     },
+    propertyChanged_: function(name, value, oldValue) {
+      if (this.reflect[name]) {
+        this.reflectPropertyToAttribute(name);
+      }
+    },
     observeArrayValue: function(name, value, old) {
       // we only care if there are registered side-effects
       var callbackName = this.observe[name];

test/js/attrs.js

@@ -8,6 +8,5 @@ htmlSuite('attributes-declarative', function() {
   htmlTest('html/publish-attributes.html');
   htmlTest('html/take-attributes.html');
   htmlTest('html/attr-mustache.html');
-  // TODO(sorvell): replace test when observe.js is updated.
-  //htmlTest('html/prop-attr-reflection.html');
+  htmlTest('html/prop-attr-reflection.html');
 });