UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Steps to reproduce the problem:
1. Setup environment with an HTML file and a CSS file
2. Load the CSS using a URL with a querystring

Example:

<link rel='stylesheet' href='http://mydomain.dev/styles.css?ver=0.01' type='text/css' media='all' />

3. Open Developer Tools
4. Right-click in Sources navigation panel under Sources tab, and select "Add Folder to Workspace". Add the folder containing HTML and CSS.
5. Browse to the CSS file in the Source navigation pane, being sure browse the network file structure
6. Right-click on the CSS file in the navigation panel and select "Map To File System Resource"
7. Filter for styles.css and select from the list of local files.
8. Use inspector to select an element, and make edits to CSS
9. Attempt to save the CSS file, or jump to a line number in local file, or type any changes to CSS in Styles inspector or Editor.

What is the expected behavior?
Changes to the CSS should save locally.

"Map To File System Resource" should change to "Remove Network Mapping"

Navigation for source code line number in Styles inspector should jump to local file. E.g., clicking on "filename:linenumber" should goto line number in local file, not network file. 

What went wrong?
Code editor panel shows a pink/reddish background color.

Hovering over warning icon next to the file name reports "changes to this file were not saved".

Clicking on "styles.css:1234" in Styles inspector doesn't take you to the corresponding line number in the local file. Instead it takes you to the network file. 

Did this work before? Yes Unknown

Chrome version: 53.0.2785.143  Channel: n/a
OS Version: OS X 10.10.5
Flash Version: Shockwave Flash 23.0 r0

Also occurs when attempting to edit a JavaScript file loaded with query string.