failing test showing infinite recursion w/_super

refs emberjs/ember.js PR #9651
[BUGFIX canary] fix this._super infinite loop

fixes a regression introduced in #9651 that would
not reset the super function, causing an infinite
loop.
Merge pull request #9678 from fivetanley/super-causing-infinite-recursion

[bugfix canary] failing test showing infinite recursion w/_super