Revert "Cache ::selection:window-inactive"

This reverts commit 688a7ae6.

Reason for revert: Issues 1223998 and 1224081

Bug: 1223998, 1224081

Original change's description:
> Cache ::selection:window-inactive
>
> The non-standard :window-inactive allows ::selection style to be
> different for active and inactive windows in Blink. Since we only had
> one pseudo element type to identify style type in the pseudo style
> cache, we used a non-caching version for the inactive case.
>
> Instead, introduce an internal pseudo id for inactive selections such
> that we can cache for inactive windows as well.
>
> Change-Id: I878d729c462de7846157691b43b242597db07221
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2983277


> Reviewed-by: Anders Hartvoll Ruud <andruud@chromium.org>
> Commit-Queue: Rune Lillesveen <futhark@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#896046}

Change-Id: I9e10c43ac9ff7f482b9edd02fda6f02149e92a97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2988602
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#896455}