Fix Console polyfill to allow Mocha.js reporters to work correctly

[darraghjburke]

The current Console polyfill only implements a limited subset of console functionality. Currently, the built in Mocha.js reporters (which print test results to the console) will not work. We are using a custom reporter as a workaround, but eventually we should fix the polyfill.

[bghgary]

Relevant code: https://github.com/BabylonJS/BabylonNative/blob/master/Apps/UnitTests/Scripts/tests.js#L1-L16