Description

This PR adds a check to avoid Shift + AltLeft throwing an exception on Linux.
The issue occurs because Shift + AltLeft is usually configured to be MetaLeft key.
The exception is thrown because the GDK event received by the engine code has its keyval pointing to MetaLeft but its keycode pointing to either Shift or Alt (depending on which was last pressed). As engine code use keycode to lookup the physical key and keyval to lookup the logical key, this results in a FlutterKeyEvent with a mismatch between logical and physical keys which leads to wrong key event being sent.

Implementation

The fix here relies on two steps:

• for each key event, check if the physical key (deduced from the keycode) is the same as one of the known modifier primary physical key.
• if it is, use the logical key (deduced from the keyval) to get the right physical key.

Related Issue

Fixes flutter/flutter#96082

Tests

Adds 1 tests