emberjs/ember.js — pull request #3040 by realityendshere (2013-07-24 19:35:39+00:00)
Title: Fix incrementProperty/decrementProperty to handle NaN

Includes fixes for incrementProperty and decrementProperty which coerce falsey increments (like NaN) to 0

Retains support for 0 increment and restores NaN increment behavior from prior to #2544

Added tests for NaN increment and decrement