Try to get keyboard-based table management to work in Safari.

[FrenjaminBanklin]

Builds on #726 and #1965.

Keyboard navigation within a Table node is mostly working properly (with some minor caveats), but due to how tab order works in Safari it is currently not possible to reach the table management controls. For example, see the following interaction in Chrome: Compare that to the following interaction in Safari:

Notice that the Tab key does not select the expandable menu in Safari. It doesn't seem to be reachable by keyboard at all.

There are also some mildly aggravating nuances with text range selection, but those can be their own issue later.