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.
This patch refactors doclint so that more checks and more generators
could be added.
This patch:
- Introduces 'Source' class, which holds file content in-memory and
allows it to be updated.
- Introduces 'Message' class - which is a pair of a text and a type.
Messages could have either 'error' type or 'warning' type.
