This is a large rework of selectors:
- Each BrowserContext now has a separate Selectors instance that has its own registrations.
Most of them share a single sharedSelectors instance, but contexts created for a connected
browser have their own instance.
- Connected browser now gets a RemoteBrowser object that encapsulates Selectors and Browser.
This Selectors object is registered with the api selectors.
- Public selectors.register api iterates over all registered Selectors channels
and registers in each of them.
- createSelector testing method migrated to ElementHandle._createSelectorForTest.
This way we test the real scenario where server is not launched
in the same node process.
Additionally, move all connect-related tests to a single file and
clean them up.
Our current tests excercise the same-process launchServer/connect
combination. This change adds tests for remote server and immediately
exposes a bug with selector engines.
This patch moves fixtures.js to base.fixtures.ts that sits next to tests. All tests get an extra import to get the base fixtures (both types and implementations).
