RFR 8152296: langtools/test/jdk/jshell/ToolReloadTest.java failing if there is no persisted history

[Jan Lahoda]

Hi,

Recently, I changed ConsoleIOContext to use UnsupportedTerminal while 
running test, to avoid setting the terminal to the raw mode. Seems that 
does not work well - some features, e.g. history, don't work correctly 
with the UnsupportedTerminal. So, I propose to change that to a dummy 
testing terminal.

Also, the tests are currently using the global Preferences, so they are 
dependent on the preexisting state and on each other - I propose to 
change that to memory based Preferences, which would be created from 
scratch for each test.

Webrev:
http://cr.openjdk.java.net/~jlahoda/8152296/webrev.00/

Any comments are welcome.

Thanks,
     Jan