RFR 8143006: JShell tool: EditPad doesn't process each line as same as inputs for jshell

[ShinyaYoshida]

Hi,
I'd like to change the behavior of SaveHandler.

When I put following into EditPad, it makes an error:

System.out.println("Hello")
System.out.println("World")
--
|  Error:
|  ';'がありません
|  System.out.println("hello")
|                             ^

It is very confusing and useless.
Because when I open EditPad after running "System.out.println("Hello")" on
jshell, the text in EditPad contains "System.out.println("Hello")" and it
could be cause of error after several editing.
(it is only happen when the invoked method returns void because
JShell#cmdEdit don't put ";" to the end of statements.)

And, above all, the user will be surprised at the input for EditPad because
it is not processed like the input for jshell.

Could you review this?
http://cr.openjdk.java.net/~shinyafox/kulla/8143006/webrev.00/

Bugs is here:
https://bugs.openjdk.java.net/browse/JDK-8143006

Regards,
shinyafox(Shinya Yoshida)