RFR: JDK-8223782: jshell parser should handle Text Blocks

[Jan Lahoda]

Hi,

In order to support text blocks (JEP 355) in JShell, it seems the main 
thing is to correctly detect snippet completion - after that, the 
ordinary javac parser should be able to handle the snippet. Proposed 
update to the completeness detection, based on how block comments are 
handled:
http://cr.openjdk.java.net/~jlahoda/8223782/webrev.00/

This also removes support for raw string literals.

The detection current marks invalid text blocks (such that they don't 
have a newline after the opening """) as incomplete - when the snippet 
is finished, the standard javac parser should handle that properly (and 
the user has an opportunity to edit the snippet to be proper).

JBS: https://bugs.openjdk.java.net/browse/JDK-8223782

What do you think?

Thanks,
     Jan