Editorial: Use consistent syntax for enum values and strings

[adam-be]

Now we just have to decide on an approach. :)

[jan-ivar]

FWIW WebIDL enumeration values are strings. Both in all observable JS ways, and in WebIDL definitions. e.g. http://w3c.github.io/webrtc-pc/#rtcpeerconnectionstate-enum

[jan-ivar]

In binding code it varies I think. In c++ implementation's they're c++ enum. In JS-implemented code they're strings. At least in our case.

[burnburn]

With #1485 I think this is done.