Parser cannot handle 'readonly' modifier on property signature

[RalfKoban]

When parsing the file https://github.com/microsoft/TypeScript/blob/master/scripts/types/ambient.d.ts, the parser cannot handle the situation properly that there is a readonly modifier on a property signature.

Snippet:

    namespace File {
        export interface VinylOptions<T extends Contents = Contents> {
            cwd?: string;
            base?: string;
            path?: string;
            history?: readonly string[];

Subsequent Property signatures aren't reported anymore. Instead, expressions are reported.