Repro for crbug.com/1370200

This illustrates the problem with confusing stepping between comma and semicolon.

Steps

1. Open DevTools
2. Click here and Step Over the code until you hit the end of the function semicolon
3. Observe that the debugger pauses exactly once on every line
4. Click here and Step Over the code until you hit the end of the function comma
5. Observe that the debugger jumps over two calls to foo without stopping