navigator.share

## System info
```
Issue occurs on: Only on Android
Plugin version: 0.3.11
Flutter doctor output:
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 1.22.5, on macOS 11.1 20C69 darwin-x64, locale es-MX)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
[✓] Xcode - develop for iOS and macOS (Xcode 12.3)
[✓] Android Studio (version 4.1)
[✓] VS Code (version 1.52.1)
[✓] Connected device (1 available)
```
## Steps to Reproduce
```
1. - use navigator.share insde the web page
```
## Logs
```
"User Agent: Mozilla/5.0 (Linux; Android 10) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/87.0.4280.141 Mobile Safari/537.36"

Macbooks-MacBook-Pro:ecart-app macbook$ flutter doctor -v
[✓] Flutter (Channel stable, 1.22.5, on macOS 11.1 20C69 darwin-x64, locale es-MX)
• Flutter version 1.22.5 at /Users/macbook/development/flutter
• Framework revision 7891006299 (5 weeks ago), 2020-12-10 11:54:40 -0800
• Engine revision ae90085a84
• Dart version 2.10.4

[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
• Android SDK at /Users/macbook/Library/Android/sdk
• Platform android-30, build-tools 30.0.3
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)
• All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 12.3)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 12.3, Build version 12C33
• CocoaPods version 1.10.0

[✓] Android Studio (version 4.1)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin installed
• Dart plugin version 201.9317
• Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b3-6915495)

[✓] VS Code (version 1.52.1)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 3.18.1

[✓] Connected device (1 available)
• SM A705MN (mobile) • R58MB1PHP4B • android-arm64 • Android 10 (API 29)

• No issues found!
```

No source file, test, or specific failure is identified. Start by reproducing navigator.share on Android with the supplied Flutter and plugin versions, then inspect the Android WebView integration; done means the behavior is characterized and the expected result is verified or the failure is narrowed to a reproducible case.

索引モデルが issue の本文から書いたものです。