Tests that breakpoints appear correct in the sidebar pane.

Script source was shown.

Set first breakpoint.
Breakpoint sidebar pane 
a.js:18  return a + b;

Set second breakpoint on the same line.
Breakpoint sidebar pane 
a.js:18:3return a + b;
a.js:18:16

Set a third breakpoint on a different line.
Breakpoint sidebar pane 
a.js:17  b = b / 2;
a.js:18:3return a + b;
a.js:18:16