Allow a const enum to be used before it's declaration

[panost]

TypeScript Version: 2.3
Regression issue with the implementation of #11935

Code

const v: Color = Color.Green;
const enum Color { Red, Green, Blue }

which compiles to:

var v = 1 /* Green */;

Expected behavior:
No error

Actual behavior:
Error on line 1: Enum Color used before its declaration.

Comments:
The above code was successfully compiled in version 2.2. So this is actually a breaking change