Add es5-shim library v3.4.0

With skip function to bypass loading in modern browsers.

Add dependency on es5-shim to OOjs and OOjs UI, and json2 to the former.

The ES5 skip function simply asserts the 'use strict' feature, which
means that all MSIE9 clients will recieve the library, which should
mostly be a no-op but will increase the load.

* Source code
  https://github.com/es-shims/es5-shim/blob/v3.4.0/es5-shim.js

As OOjs UI isn't yet tested against non-ES5 browsers using this shim,
leaving the note about likely breakage for that one.

Change-Id: I2556b39d6040d99693f6b9d469b92951ffb2e7b2
Merge "Add es5-shim library v3.4.0"