Mask 0x100 bit instead of comparison

Author: knopp

shell/platform/darwin/macos/framework/Source/FlutterChannelKeyResponder.mm

@@ -47,18 +47,20 @@ - (void)handleEvent:(NSEvent*)event callback:(FlutterAsyncKeyCallback)callback {
     case NSEventTypeKeyUp:
       type = @"keyup";
       break;
-    case NSEventTypeFlagsChanged:
-      if (event.modifierFlags < _previouslyPressedFlags) {
+    case NSEventTypeFlagsChanged: {
+      // Remove the 0x100 bit set by Cocoa when no modifiers are pressed.
+      NSEventModifierFlags modifierFlags = event.modifierFlags & ~0x100;
+      if (modifierFlags < _previouslyPressedFlags) {
         type = @"keyup";
-      } else if (event.modifierFlags > _previouslyPressedFlags &&
-                 event.modifierFlags > 0x100) {  // 0x100 is empty modifierFlags
+      } else if (modifierFlags > _previouslyPressedFlags) {
         type = @"keydown";
       } else {
         // ignore duplicate modifiers; This can happen in situations like switching
         // between application windows when MacOS only sends the up event to new window.
         return;
       }
       break;
+    }
     default:
       NSAssert(false, @"Unexpected key event type (got %lu).", event.type);
   }