UserAgent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0

Steps to reproduce the problem:
1. Open developer tools.
2. Go to console tab.
3. Paste the following code in:
   function closure(first) {
     return function inner(second) {
       debugger;
     };
   }
   closure('first')('second');
4. Press Enter.
5. Devtools should switch to sources tab and highlight the line where debugger keyword is.
6. Move your mouse pointer to the function argument named `first`. 

What is the expected behavior?
When pointing at the function argument named `first` you should see its value 'first';

What went wrong?
I see a reference error: first is not defined.

Did this work before? N/A 

Chrome version: 69.0.3497.100  Channel: stable
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: 

If we add console.log(first) before debugger statement then we can see the actual value of the argument.
 

Deleted: debugger_bug.png 36.8 KB

	debugger_bug.png 36.8 KB View Download