Helper to make the main thread wait for the children to finish before deciding on its own error code.
function makeNext(browser) {
        return function next(code) {
            exitCode += code;
            currentRun++;
            if (code === 0) {
                // Add Browser name here
                console.log(browser + ' success');
            } else {
                console.log(browser + ' fail');
            }
            if (currentRun == numberOfRuns) {
                process.exit(exitCode);
            }
        };
    }