google/traceur-compiler — pull request #1204 by arv (2014-07-24 21:00:31+00:00)
Title: Map polyfill: Only add the iterator to values() if available.

Only add the [Symbol.iterator] to the result of new Map().entries()
if entries is available in the browser.

The problem is that IE11 and old V8 with --harmony have Map but no
iterators.

Fixes #1203