[webview_flutter] Remove the upper bound from the Flutter SDK constra…

…int (flutter#2517)

As the Flutter SDK does not follow semver, an upper bound has no semantic meaning.

Using this plugin as a canary to check if anything breaks when we remove this bound.

[in_app_purchase] Fix version. (flutter#2518)

Rename test (flutter#2516)

[video_player] Add caption to VideoPlayerValue to get the current clo…

…sed caption (flutter#2487)

This PR adds closed caption support to the `VideoPlayerController` and `VideoPlayerValue`. It also adds a basic widget for displaying closed captioning on top of a `VideoPlayer`.
 
In addition, this PR:
 
* Adds tests for the caption functionality.
* Refactors the `example/lib/main.dart` file to include closed caption example, and reduce some of the boiler plate.
* Closes [flutter/flutter#49813](flutter/flutter#49813)

[google_sign_in_web] Add more detailed setup instructions. (flutter#2508

)

* Add information about the "Authorized JavaScript origins", and how to set them up in the Google APIs console.

Fixes flutter/flutter#49539

[google_maps_flutter] Fix circle and polygon stroke width (flutter#2044)

Stroke width of Polygon and Circles on Android was not independent of the screen density

[google_maps_flutter] Add steps to set up google map sdk on each plat…

…form in readme. (flutter#2507)

[webview_flutter] Fix iOS WebView not opening href with target="_blan…

…k" (flutter#2500)

Right now, flutter webview on Android will open href's with target="_blank", but iOS will not. This PR fixes this.

[url_launcher_web] Added support for mailto in url_launcher_web plugin (

flutter#2490)

* Unit tests
* Updated version and CHANGELOG

[in_app_purchase] Fix wrong _pendingCompletePurchase flag value (flut…

…ter#2504)