* `npm install` now does a full install; auxiliary installation steps
have been integrated into the `postinstall` script.
* Updated developer docs `DEVELOPER.md` accordingly; also added
instructions to dev docs for performing full tests (via `npm test`) --
same as those run on Travis.
* Reorg in tests so that JS tests can run without a Dart env.
Partly fixes#945 **under the assumption that when running JS tests
locally, `ChromeCanary` is the desired browser to use**. Note that CI
tests (Travis) still uses `DartiumWithWebPlatform` across the board
(Maybe because ChromeCanary isn't being installed?)
Fixes#1012.
Closes#1010