Searching on a modified buffer can lead to broken UI

[rafeca]

Description

When searching using multiline regexps with a modified file opened, the search results get completely broken:

Steps to Reproduce

1. Open a repo with e.g a package.json file on Atom
2. Open the package.json file and do some modifications on it without saving them.
3. Open find and replace and search for the following regexp: ,\n\s+

Expected behavior: Get some results, e.g:

Actual behavior: The UI gets broken

Reproduces how often: 100%

Versions

All versions