Typescript: Issue with debugging “this” in VS2013 when using lambdas

I am converting some TypeScript code from using a hard-coded capture of "this":

var _this = this;
var querySucceeded = function(data){
    this.doSomething(data);
}
var test = this.executeQuery().then(function(data){
    _this.querySucceeded(data);
});

to using lambdas:

var querySucceeded = function(data){
    this.doSomething(data);
}
var test = this.executeQuery().then((data) => {
    this.querySucceeded(data);
});

TypeScript compiles the JS into something resembling the first code block and everything runs fine in the browser. The issue is when debugging in Visual Studio. When I inspect "this" after the lambda, it shows the window properties, instead of the class context.

If I debug directly in the browser, it shows the local context as it should. Is this a known issue? Maybe there is a problem with the mappings between the JS file and the TS file?

I am using VS2013 Update 4 and TypeScript 1.4.