Delete does not always remove a bullet

[sachinrekhi]

When you have previously indented a bullet, the delete button no longer works to remove that line's bullet.

Since delete works to remove the bullet in the case where it has never been indented, I expect after un-indenting a subsequent bullet that delete would continue to work to remove it.

Steps for Reproduction

1. Visit beta.quilljs.com
2. Create bullet
3. Create second bullet on next line
4. Indent second bullet
5. Press delete
6. Press delete

Expected behavior:
First delete un-indents bullet
Second delete removes bullet from line

Actual behavior:
Second delete does nothing (bullet remains)

Platforms:
Chrome 50 on Mac 10.11

Version:
Quill 1.0 Beta 2