TSServer: Extra underscores in properties

TypeScript Version: nightly (2.1.0-dev.20161026)

Continuing to use ES5-style constructors found another bug - property name will contain extra underscore if it starts with 2 underscores, i'm sure it is related to language service.

Code

function MyObject(){
    this.__property = 1;
}
var instance = new MyObject();

Expected behavior:

Listing __property with two underscores, when using completion menu appears for instance.

Actual behavior:

Notes

• Appears only when property declared using this inside constructor. Prototype properties defined through prototype property and properties defined inside object literal come up fine.
• Symbol for this.<property> doesn't have 'name' attribute in declaration, but in the case of prototype.<property> it is here.

[weswigham]

This should be fixed by #16915.