Revert "(bug 45677) CSSJanus: support text-shadow and box-shadow flipping"

See I5d24c7d8456e2. This is a wontfix per Trevor and myself.

This reverts commit e457d804eb6f854baf5edfd022ce217d53d6e946

Change-Id: I886a078cbeedd5a742e9c6dfedc9bd718bab089c
Merge "Revert "(bug 45677) CSSJanus: support text-shadow and box-shadow flipping""