To aid with the migration of these classes to Kotlin (see
servo#45640), this commit removes unused
code from these classes so they don't have to be translated.
Even though `takeScreenShotOfWebPage` was deliberately unused, it's
unclear if we'd ever want to use this in the future nor if it'd take
this form (e.g., we migrate to Compose UI). Since it's all saved in the
git history anyway, we can safely remove it and retrieve it again if we
want.
Testing: There are no automated tests for Android.
Signed-off-by: veyndan <veyndan@gmail.com>