To Disable WebDriverJS promise manager for Selenium v3.0

[huan]

Selenium WebDriver 3.0 introduced a new environment variable named SELENIUM_PROMISE_MANAGER to disable the ControlFlow inside selenium, which is not necessary when we use async/await: SeleniumHQ/selenium#2969

This is according to an old bug which related with selenium webdriver 2.x non-standard promise, submit by me: SeleniumHQ/selenium#2233

And here's another issue related to this: angular/jasminewd#59

So what we need to do is to test Wechaty PuppetWeb with SELENIUM_PROMISE_MANAGER set to 0

I hope this can make some strange bug disappear, for example, sometimes BrowserDriver getChromeDriver will hang when calling selenium in unit tests in the last serval months, which will cause the unit test fail with no reason.

[huan]

nothing significantly changed after did this...