title: Flutter web view doesn't work on release mode
body: <p>I'm creating a Flutter application.</p>
  <p>If I run this application on debug mode <strong>webview</strong> works well</p>
  <p>but if I run this application on release mode it shows blank screen. It's showing <code>PlatformException</code></p>
  <p>I tried to get help from github issues but couldn't find the solution.</p>
  <p><strong>Manifest</strong></p>
  <pre><code>&lt;uses-permission android:name=&quot;android.permission.INTERNET&quot;/&gt;
  </code></pre>
  <p><strong>build.gradle</strong></p>
  <pre><code>minSdkVersion 20
  targetSdkVersion 29
  </code></pre>
  <p><strong>pubspec.yaml</strong></p>
  <pre><code>webview_flutter: ^1.0.7
  </code></pre>
  <p><strong>Error Log</strong></p>
  <pre><code>E/flutter (16872): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: PlatformException(error, java.lang.IllegalStateException: Trying to create a platform view of unregistered type: plugins.flutter.io/webview
  E/flutter (16872):      at io.flutter.plugin.platform.j$a.g(Unknown Source:229)
  E/flutter (16872):      at io.flutter.embedding.engine.i.j$a.b(Unknown Source:152)
  E/flutter (16872):      at io.flutter.embedding.engine.i.j$a.j(Unknown Source:144)
  E/flutter (16872):      at e.a.c.a.j$a.a(Unknown Source:17)
  E/flutter (16872):      at io.flutter.embedding.engine.e.b.d(Unknown Source:57)
  E/flutter (16872):      at io.flutter.embedding.engine.FlutterJNI.handlePlatformMessage(Unknown Source:4)
  E/flutter (16872):      at android.os.MessageQueue.nativePollOnce(Native Method)
  E/flutter (16872):      at android.os.MessageQueue.next(MessageQueue.java:335)
  E/flutter (16872):      at android.os.Looper.loop(Looper.java:183)
  E/flutter (16872):      at android.app.ActivityThread.main(ActivityThread.java:7660)
  E/flutter (16872):      at java.lang.reflect.Method.invoke(Native Method)
  E/flutter (16872):      at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
  E/flutter (16872):      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
  E/flutter (16872): , null, null)
  E/flutter (16872): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:581)
  E/flutter (16872): #1      MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:158)
  E/flutter (16872): &lt;asynchronous suspension&gt;
  E/flutter (16872): #2      TextureAndroidViewController._sendCreateMessage (package:flutter/src/services/platform_views.dart:1036)
  E/flutter (16872): &lt;asynchronous suspension&gt;
  E/flutter (16872): #3      AndroidViewController.create (package:flutter/src/services/platform_views.dart:742)
  E/flutter (16872): &lt;asynchronous suspension&gt;
  E/flutter (16872): #4      RenderAndroidView._sizePlatformView (package:flutter/src/rendering/platform_view.dart:195)
  E/flutter (16872): &lt;asynchronous suspension&gt;
  </code></pre>