RFR (XXS) 8080535: (ch) Expected size of Character.UnicodeBlock.map is not optimal

[Ivan Gerasimov]

Hello!

When constructing the map, the expected size is specified to be 256, but 
then 510 elements are inserted.
A new whitebox test is provided, so the next time the number of entries 
grows, the expected size will not be forgotten.

Would you please help review this fix?

BUGURL: https://bugs.openjdk.java.net/browse/JDK-8080535
WEBREV: http://cr.openjdk.java.net/~igerasim/8080535/00/webrev/

Sincerely yours,
Ivan