Fix IE11 issue in enhanced security mode on TerminalServer.

[dhirtzbruch]

The howler initialization fails and breaks the whole site`s script, in IE11 on Windows Server 2008 R2 in enhanced security mode (error message: "not implemented").
To reproduce the problem, it is enough to open a website including the howler script; even if it is not used / called anywhere.
I was not able to check the implementation by using any detection method:

• !!document.createElement('audio').canPlayType equals true (recommended here),
• typeof Audio equals function

The engine then crashes on executing new Audio().

[fpauser]

Please merge this one really soon! All apps using Howler.js that are executed on a Windows Server with enhanced security configuration break!

Details regarding Enhanced Security Configuration:
https://technet.microsoft.com/en-us/library/dd883248(v=ws.10).aspx

[goldfire]

This PR was made to the distribution file rather than the source. I've cleaned it up and committed it in ec91a63.