This is an attempt at a reland of https://github.com/flutter/flutter/pull/141396
The main changes here that are different than the original PR is fixes to wire up the `flutter test` command properly with the web renderer.
Dual Web Compile has had some issues where `flutter test` is not respecting the `--web-renderer` flag for some reason. I haven't gotten entirely to the bottom of the issue, but for now we need to rever these changes while I investigate. This reverts the following PRs:
https://github.com/flutter/flutter/pull/143128https://github.com/flutter/flutter/pull/141396
While doing this revert, I had a few merge conflicts with https://github.com/flutter/flutter/pull/142760, and I tried to resolve the merge conflicts within the spirit of that PR's change, but @chingjun I might need your input on whether the imports I have modified are okay with regards to the change you were making.
This implements dual compile via the newly available flutter.js bootstrapping APIs for intelligent build fallback.
* Users can now use the `FlutterLoader.load` API from flutter.js
* Flutter tool injects build info into the `index.html` of the user so that the bootstrapper knows which build variants are available to bootstrap
* The semantics of the `--wasm` flag for `flutter build web` have changed:
- Instead of producing a separate `build/web_wasm` directory, the output goes to the `build/web` directory like a normal web build
- Produces a dual build that contains two build variants: dart2wasm+skwasm and dart2js+CanvasKit. The dart2wasm+skwasm will only work on Chrome in a cross-origin isolated context, all other environments will fall back to dart2js+CanvasKit.
- `--wasm` and `--web-renderer` are now mutually exclusive. Since there are multiple build variants with `--wasm`, the web renderer cannot be expressed via a single command-line flag. For now, we are hard coding what build variants are produced with the `--wasm` flag, but I plan on making this more customizable in the future.
* Build targets now can optionally provide a "build key" which can uniquely identify any specific parameterization of that build target. This way, the build target can invalidate itself by changing its build key. This works a bit better than just stuffing everything into the environment defines because (a) it doesn't invalidate the entire build, just the targets which are affected and (b) settings for multiple build variants don't translate well to the flat map of environment defines.
This PR adds a test that reproduces the problem described in the linked issue: hot restart on the web seems to not update if the app being run is `const`.
The new test is expected to fail, until the `const` issue with hot restart in the web is resolved.
Expected failure mode is a 15s timeout in the following test:
```
02:31 +3 ~1 -1: Hot reload (index.html: Default) (with `const MyApp()`)): newly added code executes during hot restart [E]
TimeoutException after 0:00:15.000000: Future not completed
dart:async _startMicrotaskLoop
...
```
(And then a bunch of output that I'm not 100% sure is intended :))
## Issues
* #141588
* Move web integration tool tests to web.shard
Web integration tool tests depend on DDC changes in SDK. This change
moves them to a separate shard and subshard so CI bot configurations
can run them separately.
In particular, with will allow running those tests on dart CI flutter
HHH web bot instead of a non-web one, allowing early detection and easy
classification of issues caused by SDK changes as VM- or Web related.
* Enabled verbose mode for flaky web_tool_tests
* Split out the test changes to be commited first
