DevTools: SourceURL suffix in the script on file system should not break workspace mapping.

Drive-by: Remove extra "var" in the BreakpointsSidebarPane

BUG=365604
R=pfeldman, loislo

Review URL: https://codereview.chromium.org/258573002

git-svn-id: svn://svn.chromium.org/blink/trunk@172469 bbb929c8-8fbe-4397-9dbb-9b2b20218538