Hover Preview hides on some edits but not others

[peterflynn]

1. Select a char within a hex color
2. Leave the mouse over the hex color so hover preview is still visible
3. Type a new hex digit
4. Wiggle mouse so hover preview comes back
5. Press backspace, or delete, or Ctrl+Z

Result: Hover preview closes when you make the change in step 3, but not when you make one of the changes in step 5.

Expected: Consistent behavior.
If hover preview stays open, it should update to reflect the new text.

[peterflynn]

It turns out hover preview closes on text edit essentially by accident -- there's no code that explicitly seeks to do so. But when you insert text via the keyboard, the hidden CM textarea dispatches a scroll event for some reason. This bubbles up to the #editor-holder scroll listener, which closes the preview since it interprets the event as meaning that the whole editor has scrolled.

[gruehle]

Reviewed -- assigned to @redmunds. Should close the hover preview on "change" events. This would catch all changes, not just pasted data.

[peterflynn]

Confirmed fixed