Cannot add breakpoints to very long files

SDK/Debugger version: Not sure how to check this
Eclipse version: N/A
Chrome Version 40.0.2214.115 (64-bit)
Google Chrome/V8 Embedder + version:
[For WebKit (WIP) protocol] Backend version:  Not sure how to check this
OS + version:

Not sure if this has to do with very long files or long files with source maps.

What steps will reproduce the problem?
1. Have a fairly large ember-cli project, with several dependencies.
2. Host it with `ember-serve`, so it serves a source map.
3. Open it with Chrome
4. Open the debugger
5. Open one of the core ember libraries, like ember.js, and try to add a 
breakpoint.

What is the expected result?
Should add a breakpoint like usual.

What happens instead?
It unclicks itself:
http://i.imgur.com/vlA9JYN.gif

Please provide any additional information below. If possible, attach a
(reduced) test-case.

Original issue reported on code.google.com by nameless...@gmail.com on 27 Feb 2015 at 6:18

beefeather / chromedevtools

Cannot add breakpoints to very long files #105