fix(timeout): throw traceable TimeoutError

[kwonoj]

Description:
This PR updates behaivor of timeout operator for better readibility of stack trace when TimeoutError thrown.

For example, with given code snippet

Rx.Observable.never().timeout(10).subscribe(console.log.bind(console));

stacktrace will be like below

D:\github\rxjs\dist\cjs\scheduler\AsyncScheduler.js:45
            throw error;
            ^
TimeoutError: Timeout has occurred
    at new TimeoutError (D:\github\rxjs\dist\cjs\util\TimeoutError.js:17:26)
    at TimeoutSubscriber.notifyTimeout (D:\github\rxjs\dist\cjs\operator\timeout.js:99:40)
    at AsyncAction.TimeoutSubscriber.dispatchTimeout [as work] (D:\github\rxjs\dist\cjs\operator\timeout.js:75:20)
    at AsyncAction._execute (D:\github\rxjs\dist\cjs\scheduler\AsyncAction.js:111:18)
    at AsyncAction.execute (D:\github\rxjs\dist\cjs\scheduler\AsyncAction.js:86:26)
    at AsyncScheduler.flush (D:\github\rxjs\dist\cjs\scheduler\AsyncScheduler.js:36:32)
    at ontimeout (timers.js:365:14)
    at tryOnTimeout (timers.js:237:5)
    at Timer.listOnTimeout (timers.js:207:5)

which loses original context of code but shows stack trace of async execution context (vary by scheduler specified). This makes hard to track down unhandled exception since it's disconnected to original codebases. Instead, this PR creates error to contain stack traces nearby originall caller, emits like below

D:\github\rxjs\dist\cjs\scheduler\AsyncScheduler.js:45
            throw error;
            ^
TimeoutError: Timeout has occurred
    at new TimeoutError (D:\github\rxjs\dist\cjs\util\TimeoutError.js:17:26)
    at NeverObservable.timeout (D:\github\rxjs\dist\cjs\operator\timeout.js:24:32)
    at Object.<anonymous> (D:\github\rxjs\dummy.js:3:23)
    at Module._compile (module.js:573:32)
    at Object.Module._extensions..js (module.js:582:10)
    at Module.load (module.js:490:32)
    at tryModuleLoad (module.js:449:12)
    at Function.Module._load (module.js:441:3)
    at Module.runMain (module.js:607:10)
    at run (bootstrap_node.js:382:7)

allows bit more easier tracking.

Related issue (if exists):

[coveralls]

Coverage increased (+0.0004%) to 97.686% when pulling 29bbd60 on kwonoj:fix-timeout into e0cf882 on ReactiveX:master.

[jayphelps]

wow! this is awesome! LGTM

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.