Test CSS environment variables when "window-controls-overlay" in display-override member

Description

This test validates that when in "window-controls-overlay" mode, the 'titlebar-area-*' CSS environment variables match the values returned by navigator.windowControlsOverlay.getTitlebarAreaRect().

Manual Test Steps:

  1. Install this app, and toggle into "window-controls-overlay" mode.
  2. Upon toggling into "window-controls-overlay" mode, the test will validate that the CSS enviroment variable values match the JavaScript API.
Note: This test will automatically timeout and fail if not completed within 60 seconds.