fix an issue that array observer not working if it is set on the

prototype.

Author: frankiefu

src/instance/properties.js

@@ -26,9 +26,9 @@
         for (var i=0, l=n$.length, n; (i<l) && (n=n$[i]); i++) {
           o.addPath(this, n);
           // observer array properties
-          var pd = Object.getOwnPropertyDescriptor(this.__proto__, name);
+          var pd = Object.getOwnPropertyDescriptor(this.__proto__, n);
           if (pd && pd.value) {
-            this.observeArrayValue(name, pd.value, null);
+            this.observeArrayValue(n, pd.value, null);
           }
         }
         for (var i=0, l=pn$.length, n; (i<l) && (n=pn$[i]); i++) {

test/html/property-array-changes.html

@@ -16,12 +16,16 @@
         (function() {
           var a = [], a1 = [];
           Polymer('x-test', {
+            b: [],
             ready: function() {
               this.a = a;
             },
             aChanged: function() {
               this.nextTest();
             },
+            bChanged: function() {
+              this.nextTest();
+            },
             currentTest: 0,
             getCurrentTest: function() {
               return this['test' + this.currentTest];
@@ -68,6 +72,10 @@
             },
             test6: function() {
               chai.assert.equal(this.a.length, 1, 'old array properly unobserved');
+              this.b.push(1);
+            },
+            test7: function() {
+              chai.assert.equal(this.b.length, 1, 'noticed array addition');
             }
           });
         })();