[constables] RFR of constants API

[Vicente Romero]

Hi all,

Please review the current proposal of the constants API, which are 
nominal descriptor types defined in pkg java.lang.invoke.constant. The 
code can be found at [1]. This API is being developed in the context of 
JEP 303: Intrinsics for the LDC and INVOKEDYNAMIC Instructions [2]

Thanks in advance for your comments,
Vicente

[1] http://cr.openjdk.java.net/~vromero/constant.api/webrev.00
[2] http://openjdk.java.net/jeps/303