RFR: 6614237: missing codepage Cp290 at java runtime

[Xueming Shen]

Masayoshi,

Would you please help review this change? The changeset also adds the requested Cp300.

webrev:
http://cr.openjdk.java.net/~sherman/6614237/webrev/

original mapptables:
http://cr.openjdk.java.net/~sherman/6614237/290/
http://cr.openjdk.java.net/~sherman/6614237/300/

regression tests:
http://cr.openjdk.java.net/~sherman/6614237/closed

Thanks!
-Sherman