Fixes string parsing in strider:

TypeError: Cannot read property 'length' of null
    at StringDecoder.detectIncompleteChar (string_decoder.js:129:18)
        at StringDecoder.write (string_decoder.js:99:28)
            at Interface._normalWrite (readline.js:303:30)
                at Interface.write (readline.js:294:49)
                    at Interface.Progress.rl.clearLine (/.strider/526174786c0e130a0000000a.strider-cd.strider/node_modules/mocha-selenium/lib/progress.js:29:10)
                        at Object.Progress.render (/.strider/526174786c0e130a0000000a.strider-cd.strider/node_modules/mocha-selenium/lib/progress.js:51:13)
                            at wrapper [as _onTimeout] (timers.js:252:14)
                                at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)