## Description

This removes all of the comments that are of the form "so-and-so must not be null" or "so-and-so must be non-null" from the cases where those values are defines as non-nullable values.

This PR removes them from the library in the repo that don't have anything to do with the framework.

This was done by hand, since it really didn't lend itself to scripting, so it needs to be more than just spot-checked, I think. I was careful to leave any comment that referred to parameters that were nullable, but I may have missed some.

In addition to being no longer relevant after null safety has been made the default, these comments were largely fragile, in that it was easy for them to get out of date, and not be accurate anymore anyhow.

This did create a number of constructor comments which basically say "Creates a [Foo].", but I don't really know how to avoid that in a large scale change, since there's not much you can really say in a lot of cases.  I think we might consider some leniency for constructors to the "Comment must be meaningful" style guidance (which we de facto have already, since there are a bunch of these).

## Related PRs
- https://github.com/flutter/flutter/pull/134984
- https://github.com/flutter/flutter/pull/134991
- https://github.com/flutter/flutter/pull/134992
- https://github.com/flutter/flutter/pull/134993

## Tests
 - Documentation only change.

This PR fixes the issue #108614 
Particularly this behaviour https://github.com/flutter/flutter/issues/108614#issuecomment-1645231915

Fixes TODO in the analyzer script :)

- `ui_web.warmupEngine`
- `ui_web.setPluginHandler`
- `ui_web.debugEmulateFlutterTesterEnvironment`

- Use `Uri.parse()` to extract pathname.
- Remove unused code from `utils.dart`.
- Add test for URL encoding.

(need to wait for https://github.com/flutter/flutter/pull/126851 to make it into Google3)

To avoid confusion and unpredictable errors (e.g. https://github.com/flutter/flutter/issues/127462), I'm adding this assert to disallow this pattern.

Fixes https://github.com/flutter/flutter/issues/127462

Remove the following APIs and export them directly from `dart:ui_web`:
- `urlStrategy` getter and setter
- `HashUrlStrategy`
- `PlatformLocation` and `BrowserPlatformLocation` (keep the façades for non-web platforms)

Depends on https://github.com/flutter/engine/pull/42043
Depends on https://github.com/flutter/engine/pull/42252

Part of https://github.com/flutter/flutter/issues/126831

This PR fixes the dropping of both the `path` and `search` fields from the platform location in the URL when using Flutter Web and brings it in par with similar technologies (e.g. React Router).
It allows developers to keep the original path and/or search parameters in the URL, which are perfectly valid even while fragment routing is present.

**Example use case:**
Call a Flutter Web app with initial config parameters in the URL: 
`http://my-flutter.app/?skipIntro=true`

**Example:**
Before initial routing:
`http://localhost:45389/?foo=bar`
After routing:
`http://localhost:45389/#/menu`
After routing (with fix):
`http://localhost:45389/?foo=bar#menu`

Fixes #116415

This is based off (and dependent on) these changes in the web engine that expose web-specific APIs: https://github.com/flutter/engine/pull/40608

* Fix typos

* lowercase animated & opacity

* Undo typo fix

---------
Co-authored-by: Michael Goderbauer <goderbauer@google.com>

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_driver`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_goldens`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_goldens_client`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_localizations`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_test`

* Use `curly_braces_in_flow_control_structures` for `packages/flutter_web_plugins`

* fix comments

* Use `curly_braces_in_flow_control_structures` for `packages/integration_test`

* fix indentation

This adds avoid_dynamic_calls to the list of lints, and fixes all instances where it was violated.

Importantly, this lint is NOT turned on for flutter/packages/test, because those changes are happening in another PR: #84478

This reverts commit 35ad43f2.

This reverts commit c26ed03c.

* Migrate to ChannelBuffers.push

* Move TestDefaultBinaryMessenger to its own file

* Apply deprecations and fix usages

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.

This reverts commit 8749d955.

In principle this is backwards compatible; I just merged all the classes into one and deprecated everything that became redundant as a result.

Force opt-in flutter test platform to null safety for repo testing