Fixes Polymer#120.

Author: sorvell

src/declaration/properties.js

@@ -11,20 +11,27 @@
 
   // element api
 
+  var observationBlacklist = ['attribute'];
+
   var properties = {
     inferObservers: function(prototype) {
       // called before prototype.observe is chained to inherited object
       var observe = prototype.observe, property;
       for (var n in prototype) {
         if (n.slice(-7) === 'Changed') {
-          if (!observe) {
-            observe  = (prototype.observe = {});
+          property = n.slice(0, -7);
+          if (this.canObserveProperty(property)) {
+            if (!observe) {
+              observe  = (prototype.observe = {});
+            }
+            observe[property] = observe[property] || n;
           }
-          property = n.slice(0, -7)
-          observe[property] = observe[property] || n;
         }
       }
     },
+    canObserveProperty: function(property) {
+      return (observationBlacklist.indexOf(property) < 0);
+    },
     explodeObservers: function(prototype) {
       // called before prototype.observe is chained to inherited object
       var o = prototype.observe;

test/html/property-changes.html

@@ -24,7 +24,7 @@
       <script>
         (function() {
           var changes = 0;
-          var doneChanges = 2;
+          var doneChanges = 3;
           function checkDone() {
             if (doneChanges == ++changes) {
               done();
@@ -33,7 +33,12 @@
 
           Polymer('x-test', {
             bar: '',
+            attributeChangedCount: 0,
             ready: function() {
+              this.attribute = 'foo';
+              this.deliverChanges();
+              chai.assert.equal(this.attributeChangedCount, 0, 'attributeChanged does not observe property attribute');
+              this.setAttribute('nog', 'nog');
               this.bar = 'bar';
               setTimeout(function() {
                 this.zonk = 'zonk';
@@ -46,6 +51,11 @@
             zonkChanged: function() {
               chai.assert.equal(this.zonk, 'zonk', 'change calls *Changed without prototype value')
               checkDone();
+            },
+            attributeChanged: function() {
+              this.attributeChangedCount++;
+              chai.assert.equal(this.getAttribute('nog'), 'nog', 'attributeChanged called in response to an attribute value changing')
+              checkDone();
             }
           });
         })();