Avoid non-bubbling event gotchas with binding.

test/unit/bind-elements.html

@@ -143,3 +143,47 @@
     }
   });
 </script>
+
+<script>
+  Polymer({
+    is: 'x-notifies1',
+    properties: {
+      notifies: {
+        notify: true
+      }
+    }
+  });
+</script>
+
+<dom-module id="x-notifies2">
+  <template>
+    <x-notifies1 id="notifies1"></x-notifies1>
+  </template>
+</dom-module>
+<script>
+  Polymer({
+    is: 'x-notifies2',
+    properties: {
+      notifies: {
+        notify: true
+      }
+    }
+  });
+</script>
+
+<dom-module id="x-notifies3">
+  <template>
+    <x-notifies2 id="notifies2" notifies="{{shouldNotChange}}"></x-notifies2>
+  </template>
+</dom-module>
+<script>
+  Polymer({
+    is: 'x-notifies3',
+    properties: {
+      shouldNotChange: {
+        observer: 'shouldNotChangeChanged'
+      }
+    },
+    shouldNotChangeChanged: function() { }
+  });
+</script>