Fixed extent lists cannot handle infinite extent - #8885

…r#189622)

`--web-define` substitution of `{{PLACEHOLDER}}` tokens in
`web/index.html` and
`flutter_bootstrap.js` worked in debug `flutter run` (serve-time
substitution in
`WebAssetServer`) and in `flutter build web` (`webDefine:`-prefixed
entries in the
build `Environment` consumed by the `WebTemplatedFiles` target), but not
in
`flutter run --profile` or `--release`: `ResidentWebRunner` stored the
parsed
defines in `_webDefines` and then omitted them from both
`WebBuilder.buildWeb()`
calls in the non-debug branch, and `ReleaseAssetServer` serves the build
output
verbatim with no serve-time templating, so the placeholders were never
replaced.

This passes `webDefines` to both `buildWeb()` call sites (the initial
build in
`run()` and the rebuild on hot restart), matching how `flutter build
web` already
passes them. Debug `--wasm` runs take the same branch and are fixed as a
side
effect. `flutter drive` never forwarded web-defines in any mode, so the
flag is
now plumbed through `DriverService.start()` into `WebDriverService` and
on to the
web runner.

Added unit tests assert that the build `Environment` receives the
`webDefine:`-prefixed defines in profile mode, on the rebuild after a
hot restart
in release mode, and in debug `--wasm` mode; that `WebDriverService`
forwards
web-defines to the web runner; and that the drive command forwards
`--web-define`
values to `DriverService.start()`.

Added end-to-end tests run the real tool against a fixture project whose
`web/index.html` and `web/flutter_bootstrap.js` contain `{{MY_VERSION}}`
and
`{{API_URL}}` placeholders: `flutter build web` in debug/profile/release
must
substitute them in `build/web/index.html` and
`build/web/flutter_bootstrap.js`,
and `flutter run -d web-server` in debug/profile/release must serve
substituted
HTML, including after hot reload (debug) and hot restart (all three
modes).
Existing web-define coverage for `flutter build web` and debug-mode
serving is
unchanged and passing.

Fixes flutter#8885 (was closed, but the problem was actually this - the flag
was only passed on specific run configurations). Also related to PR
flutter#175805 and issue flutter#127853

## Pre-launch Checklist

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- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

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---------

Co-authored-by: Ben Konyi <bkonyi@google.com>