editor: bold and link on Windows

[hejtful]

To reproduce (Windows and Chrome/Firefox):

1. Write at least 2 consecutive words in a Text line. You can also use existing Text and continue.
2. Mark one word as bold.
3. Double-click on that word
4. Mark the word as a link using the toolbar or the shortcut.

Note: On double-click, Windows selects the word and the empty space next to it. This confuses Slate when the selected word is bold or italic, but the empty space next to it isn't.