Es6 Shim: 0.29.0 Release

Why the minor version was bumped - Ensure that ES3 browsers get both Object.is and Object.assign - Ensuring Number.parseInt === parseInt (failed in FF 37)

Enhancements - Improve Object.assign to avoid leaking arguments in v8 - a little more accurate Math.cbrt (#335) - Avoid reassigning argument variables to avoid deoptimizations - Ensure that shallowly wrapped Maps’ and Sets’ prototypes aren't one level too far away.

Testing - Test on io.js v1.7 and v1.8 - Update chai and use new matchers - Test cleanups - Adding Symbol.unscopables tests - Adding tests to ensure that default iterators on builtins === the appropriate prototype function.