RFR: 8230768: Arrays of SoftReferences in MethodTypeForm should not be @Stable

[Claes Redestad]

Hi,

please review this patch to remove @Stable from two arrays in
MethodTypeForm. These were marked as @Stable in an earlier
incarnation of the code when the contents was not SoftReference,
but @Stable does not make sense for SoftReferences and might even
be detrimental.

I also did some incidental cleanup of the code.

Bug:    https://bugs.openjdk.java.net/browse/JDK-8230768
Webrev: http://cr.openjdk.java.net/~redestad/8230768/jdk.00/

Thanks!

/Claes