Trying to fix the problem with corrupted message in the tests

Author: justinmc

lib/web_ui/lib/src/engine/platform_dispatcher.dart

@@ -534,11 +534,11 @@ class EnginePlatformDispatcher extends ui.PlatformDispatcher {
         const MethodCodec codec = StandardMethodCodec();
         final MethodCall decoded = codec.decodeMethodCall(data);
         switch (decoded.method) {
-          case 'enableContextMenu':
+          case 'ContextMenu.enableContextMenu':
             flutterViewEmbedder.enableContextMenu();
             replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;
-          case 'disableContextMenu':
+          case 'ContextMenu.disableContextMenu':
             flutterViewEmbedder.disableContextMenu();
             replyToPlatformMessage(callback, codec.encodeSuccessEnvelope(true));
             return;

lib/web_ui/test/engine/platform_dispatcher_test.dart

@@ -105,7 +105,7 @@ void testMain() {
       ui.PlatformDispatcher.instance.sendPlatformMessage(
         'flutter/contextmenu',
         codec.encodeMethodCall(const MethodCall(
-          'enableContextMenu',
+          'ContextMenu.enableContextMenu',
         )),
         completer.complete,
       );
@@ -124,7 +124,7 @@ void testMain() {
       ui.PlatformDispatcher.instance.sendPlatformMessage(
         'flutter/contextmenu',
         codec.encodeMethodCall(const MethodCall(
-          'disableContextMenu',
+          'ContextMenu.disableContextMenu',
         )),
         completer.complete,
       );