dom-repeat does not always notify paths of properties listed in "observe"

[digint]

Description

In dom-repeat, all properties listed in the "observe" property are not always correctly notified in the template content, and no property effects are generated.

Live Demo

http://jsbin.com/kucotolebo/edit?html,output

Steps to Reproduce

Example:

<template is="dom-repeat" items="[[myArrayOfObjects]]" observe="myProp">
  <my-element data="[[item]]"></my-element>
</template>

1. create element my-element which displays data.myProp
2. this.set('myArrayOfObjects.0.myProp', 'somevalue')

Expected Results

As this is not documented in the dom-repeat API, I expect all properties to be always notified (not only if the observed property triggers re-sort and/or re-filter)

Actual Results

If myProp sees an observable change, data.myProp in my-element is not notified and does not generate property effects.

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari 9
• Safari 8
• IE 11

(probably all browsers affected)

Versions

• Polymer: v2.0.1