According to https://en.wikipedia.org/wiki/Comparison_of_layout_engines_%28ECMAScript%29#ECMAScript_version_support Chrome has only partial ES5 support.

According to http://www.robertnyman.com/javascript/index.html#javascript-getters-setters-object-defineproperty-compatibility then Chrome 9.5 onwards has support for getters and setters.

Looking at http://kangax.github.io/es5-compat-table/ also agrees.

Interestingly, CONTRIBUTING.md says we should use get and set.

I don't know enough about ES5 to know how much we'd want to use, but it seems like we could use at least get/set as with the webrtc platform requirements, we're not going to be able to use support older browsers.