RFR [9] 8141615: Add new public methods to sun.reflect.ConstantPool

[Konstantin Shefov]

Hello

Please review an enhancement to add three new methods to 
sun.reflect.ConstantPool class.
The following methods are suggested:

public String[] getNameAndTypeRefInfoAt(int index) - returns string 
representation of name and type from a NameAndType constant pool entry 
with the specified index

public String[] getInvokedynamicRefInfoAt(int index) - returns string 
representation of name and type from an InvokeDynamic constant pool 
entry with the specified index

public Tag getTagAt(int index) - returns a Tag enum instance of a 
constant pool entry with the specified index

These three methods could be used for testing API working with constant 
pool, e.g. JVMCI.

JBS: https://bugs.openjdk.java.net/browse/JDK-8141615
Webrev hotspot: 
http://cr.openjdk.java.net/~kshefov/8141615/hotspot/webrev.00
Webrev jdk: http://cr.openjdk.java.net/~kshefov/8141615/jdk/webrev.00

Thanks
-Konstantin