* fix: ensure child window transparency works
Windows opened via window.open and intecepted via setWindowOpenHandler
or the `new-window` event should (a) have the correct background color
and (b) that background color should be transparent if specified.
The changes in api_web_contents fix (a) and the changes in
web_contents_preferences fix (b).
Notes: Child windows with specified background colors or transpency now
work as intended
* fix: set background_color in blink prefs apply logic
* chore: update for PR comments
089ac8180f