RFR 8225789: Empty method parameter type should generate ClassFormatError

[Harold Seigel]

Hi,

Please review this JDK-13 fix for JDK-8225789.  The fix ensures that a 
ClassFormatError exception gets thrown for unqualified names that do not 
contain at least one Unicode code point.  This is required by section 
4.2.2 'Unqualified Names' 
<https://docs.oracle.com/javase/specs/jvms/se12/html/jvms-4.html#jvms-4.2> 
of the JVM Spec.

Open Webrev: 
http://cr.openjdk.java.net/~hseigel/bug_8225789_13/webrev/index.html

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8225789

The fix was regression tested by running Mach5 tiers 1 and 2 tests and 
builds on Linux-x64, Solaris, Windows, and Mac OS X, by running Mach5 
tiers 3-5 tests on Linux-x64, and JCK lang and VM tests on Linux-x64.

Thanks, Harold