angular/angular.js — pull request #9712 by teropa (2014-10-21 09:28:19+00:00)
Title: docs(ngRepeat): improve description of tracking and duplicates

Add a section to the documentation on how tracking between items and DOM
elements is done, and why duplicates are not allowed in the collection.

Describe how the default tracking behaviour can be substituted with track by.

Tweak the wording in the `track by` section to discuss “tracking expressions”
instead of “tracking functions”.

Closes #8153