Uses of `symbolName` in diagnostics are ugly for dynamic names

TypeScript Version: master

Code

const foo = Symbol.for("foo");
class C {
    private [foo]: number;
}

Expected behavior:

src/a.ts(3,13): error TS6133: '[foo]' is declared but its value is never read.

Actual behavior:

src/a.ts(3,13): error TS6133: '__@foo@19374' is declared but its value is never read.