Previously we grepped all hand-written Dart code and ran analyzer in strong mode against it.
Now we run it against transformed playground apps, which:
1. does not analyze unnecessary code (we primarily care about stuff that runs in the browser)
2. analyzes generated code, which does run in the browser and which we failed to analyze in the previous version of the build
Closes#6436
* `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