[video_player] Ensures autoplay is false on the web. (#4961)

### Description

This PR changes the initialization of the `video` element used by the web implementation of the video_player plugin to **ensure the `autoplay` attribute is set to _**false**_**, as expected by the code.

### Issues

* Fixes flutter/flutter#135194
* ~~May be the root cause of flutter/flutter#130147~~ (it isn't, I've seen the integration test failing again)

Author: ditman

packages/video_player/video_player_web/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.1.1
+
+* Ensures that the `autoplay` attribute of the underlying video element is set
+  to **false**.
+
 ## 2.1.0
 
 * Adds web options to customize the control list and context menu display.

packages/video_player/video_player_web/example/integration_test/video_player_test.dart

@@ -31,8 +31,11 @@ void main() {
 
       expect(video.controls, isFalse,
           reason: 'Video is controlled through code');
-      expect(video.getAttribute('autoplay'), 'false',
-          reason: 'Cannot autoplay on the web');
+      expect(video.autoplay, isFalse,
+          reason: 'autoplay attribute on HTMLVideoElement MUST be false');
+      // see: https://developer.mozilla.org/en-US/docs/Glossary/Boolean/HTML
+      expect(video.getAttribute('autoplay'), isNull,
+          reason: 'autoplay attribute on video tag must NOT be set');
       expect(video.getAttribute('playsinline'), 'true',
           reason: 'Needed by safari iOS');
     });

packages/video_player/video_player_web/lib/src/video_player.dart

@@ -63,12 +63,13 @@ class VideoPlayer {
       ..autoplay = false
       ..controls = false;
 
-    // Allows Safari iOS to play the video inline
+    // Allows Safari iOS to play the video inline.
+    //
+    // This property is not exposed through dart:html so we use the
+    // HTML Boolean attribute form (when present with any value => true)
+    // See: https://developer.mozilla.org/en-US/docs/Glossary/Boolean/HTML
     _videoElement.setAttribute('playsinline', 'true');
 
-    // Set autoplay to false since most browsers won't autoplay a video unless it is muted
-    _videoElement.setAttribute('autoplay', 'false');
-
     _videoElement.onCanPlay.listen((dynamic _) {
       if (!_isInitialized) {
         _isInitialized = true;

packages/video_player/video_player_web/pubspec.yaml

@@ -2,7 +2,7 @@ name: video_player_web
 description: Web platform implementation of video_player.
 repository: https://github.com/flutter/packages/tree/main/packages/video_player/video_player_web
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+video_player%22
-version: 2.1.0
+version: 2.1.1
 
 environment:
   sdk: ">=3.1.0 <4.0.0"