[webview_flutter] Webview should have transparent background #29300
Description
Showing a web view inside an iOS popup looks weird because popup is semi transparent and web view background is white opaque.
By default the plugin should have a transparent background.
[✓] Flutter (Channel stable, v1.2.1, on Mac OS X 10.14.3 18D109, locale fr-FR)
• Flutter version 1.2.1 at /Users/jaumard/flutter
• Framework revision 8661d8aecd (4 weeks ago), 2019-02-14 19:19:53 -0800
• Engine revision 3757390fa4
• Dart version 2.1.2 (build 2.1.2-dev.0.0 0a7dcf17eb)
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
• Android SDK at /Users/jaumard/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-28, build-tools 28.0.3
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
• All Android licenses accepted.
[✓] iOS toolchain - develop for iOS devices (Xcode 10.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.1, Build version 10B61
• ios-deploy 1.9.4
• CocoaPods version 1.5.3
[✓] Android Studio (version 3.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 33.3.1
• Dart plugin version 182.5215
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
[✓] IntelliJ IDEA Ultimate Edition (version 2018.3.4)
• IntelliJ at /Applications/IntelliJ IDEA.app
• Flutter plugin version 32.0.3
• Dart plugin version 183.5429.25
• No issues found!