Adjacent lists require separate containers

[pshatara90]

If you create 2 lists - one unordered, the followed by an ordered list - without a line break in between them, Quill is putting each <li> under the same <ol> creating a weird rendering condition. See screenshot.

Steps for Reproduction

1. Create an unordered list and add some content
2. Add a linebreak (see second list item)
3. click backspace to remove list formatting
4. Create an ordered list
5. See that first ordered list item has value 2 (with css applied to data-list="ordered" element) and that element is wrapped by the same <ol> as the unordered list.

Expected behavior:
Lists should be held by separate <ol> containers

Actual behavior:
Lists rendered in same <ol>

Platforms:
Chrome

Version:
2.0.0-rc.3

[luin]

Duplication of #979