Verify that breakpoints are moved appropriately
Running: addFileSystem
Running: setBreakpointInFileSystemUISourceCode
file:///var/www/devtools/persistence/resources/foo.js:2
Running: addFileMapping
http://127.0.0.1:8000/devtools/persistence/resources/foo.js:2
Running: removeFileMapping
file:///var/www/devtools/persistence/resources/foo.js:2
http://127.0.0.1:8000/devtools/persistence/resources/foo.js:2