Fix copy/paste in the Linux embedding (#18624)

The recent refactoring to support headless mode accidentally passed
nullptr instead of the window (if any) to the platform handler that
manages clipboard interactions, causing it to be broken.

Fixes https://github.com/flutter/flutter/issues/58035
https://dart.googlesource.com/external/github.com/flutter/engine/+/a03c752a81e310621897b8f6a3cd634e2429b711
1 file changed
tree: bc160d8a06c56661abe36e0df78c4c04fcd3c82d
  1. commits.json