8145486: jjs should support documentation key shortcut in interactive mode
Reviewed-by: mhaupt, hannesw
SyntaxError: Invalid JSON: <json>:1:12 Trailing comma is not allowed in JSON
{ "a": 333, }
^
SyntaxError: Invalid JSON: <json>:1:8 Trailing comma is not allowed in JSON
[ 4343, ]
^