GoToDef should go to the matching signature and not the signature block

[mhegazy]

export declare function equal(actual: any, expected: any);
export declare function equal(actual: any, expected: any, message: string);

equal(1, 3);
equal(1, 3, "4"); 

go to def on each should go to the matching signature, currently both go to the last one.

[mhegazy]

Have not seen other complains from the current behavior. closing.