It's very bad to have 'unhandled promise rejection' that can't be
handled in user code. These errors will exit node process in a near
future.
This patch avoids 'unhandled promise rejection' while sending protocol
messages.
This patch:
- introduces `puppeteer:error` debug scope and starts using it for all
swalloed errors.
- makes sure that every `client.send` method is either awaited or its
errors are handled.
- starts return promises from Request.continue() and Request.abort().
- starts swallow errors from Request.contine() and Request.abort().
The last is the most important part of the patch. Since
`Request.continue()` might try to continue canceled request, we should
disregard the error.
Fixes#627.
This patch
- rolls chromium to 492629
- migrates connection establishing to use browser target. This migration means
that now we have a single websocket connection to browser (implemented
in Connection class). A connection to a particular target is
incapsulated in a new Session class.
