noUnusedLocals: errors on variables that are used

[DickvdBrink]

Version: 2.0.0-dev.20160629

Compile below code with --noUnused Locals
tsc --noUnusedLocals test.ts

class test {
    public testMethod() {
        var that = this;

        setTimeout(() => {
            that.testMethod();
        }, 100);
    }
}

Expected
No errors but got one for test.ts(5,13): error TS6133: 'that' is declared but never used.

[mhegazy]

duplicate of #9403