Hitting tab on plus sign should create an indented node

[taramk]

If your cursor is at the plus sign and you start typing, it creates a new node. Similarly, from the plus sign, users should be able to hit tab then start typing to create a new indented node. Instead, hitting tab expands my url bar (in Safari).

To reproduce:
Put your cursor at the plus sign
Hit tab

https://recordit.co/wGB3XQHWYd

[taramk]

looks good to me! it only indents at most one level beyond the node above it, but that's probably fine or maybe even intentional