I think this is a recent regression related to tieing ContentViews with particular Sidebars. Following the steps to reproduce I select a breakpoint and I would expect that breakpoint to be selected after the click. Instead the inspector makes the resource the breakpoint belongs to selected.
1. Inspect <http://pecoraro.apple.com/source-map-tests/reasonable-example/>
2. Set a breakpoint in SourceMapResource script-1.js:14
3. Switch to the Debugger sidebar
4. Reload the page
=> content view switches to the DOM content view, I'd expect it to keep showing the Script
5. Select the Breakpoint
=> sidebar selects the script resource instead of the breakpoint I just clicked on
Created attachment 204928 [details]
Comment on attachment 204928 [details]
r=me. Seems a little obtuse, but it looks fine to me.