Slate: Shift-select with the arrow keys fails when selecting toward an inline void node

[bengotow]

Hey folks! This one's a bit odd. GIF below! In the GIF, I am holding down the shift key the whole time. (I haven't attached a JSFiddle because it's reproduced on http://slatejs.org/#/emojis.)

Observations:

• Happens in both Firefox Beta and stable Chrome.
• You can shift-select with the arrow keys away from an inline void node. Eg: "shift right arrow" past the last void node, or "shift left arrow" before the first void node works.
• You cannot shift-select with the arrow keys toward an inline void node.

[CameronAckermanSEL]

Might be similar to https://github.com/ianstormtaylor/slate/issues/1502

[ms88privat]

Also related?
https://github.com/ianstormtaylor/slate/pull/913

[conorcussell]

This is happening because nextText is the zero-width text node slate inserts. As a result, the condition is true and we collapse the selection forward instead of extending it.

I've made a PR which deals with this issue, I still need to check it deals with the other cases and doesn't cause any regressions.