Here's a bunch of bugs we found during our bug bash that are related to tab to hyperlink and mark mode

• If Shift+tab causes scroll and new selection is on multiple lines, we scroll to show the "end" (should show the whole thing)
• Shift+tab skips over hyperlink that is (end) partially included in top row of view
• If a selection exists, mark mode should happen on the existing selection (Polish MarkMode interactions with ExpandSelectionToWord and existing selection #13893)
• Ctrl+enter on random selection clears selection. Maybe it should try to treat selection as a URL?
• Mark mode --> move to middle of word --> ExpandSelectionToWord --> Shift+Right/Left --> weird updated selection (Polish MarkMode interactions with ExpandSelectionToWord and existing selection #13893 )
• [Follow-up] Polish keyboard navigation to hyperlinks #13494 (comment)
• remove _selectionIsTargetingUrl, instead check if new selection matches old selection. If so, skip it.