RFR: 8238863: Refactor out static initialization from Dict constructors

[Claes Redestad]

Hi,

I stumbled upon some static initialization in Dict and after reading it
twice I think we would be better off by spelling it out as a constant
rather than calculating it at runtime.

Webrev: http://cr.openjdk.java.net/~redestad/8238863/open.00/
Bug:    https://bugs.openjdk.java.net/browse/JDK-8238863

Testing: tier1+2

/Claes