Review request for JDK-8066225

[Attila Szegedi]

Please review JDK-8066225 at <http://cr.openjdk.java.net/~attila/8066225/webrev.00> for <https://bugs.openjdk.java.net/browse/JDK-8066225>

I changed SwitchNode.isInteger() method to SwitchNode.isUniqueInteger() (it returns true if all cases are 32-bit integer constants, *and* there are no repetitions among them). Duplicates will have us switch to if/else compilation instead of tableswith/lookupswitch. 

Also, instead of having this method's return value being calculated on every invocation (it is invoked at least 4 times; potentially more in LocalVariableTypesCalculator if it's in a loop), I moved the calculation to only happen once, in FoldConstants (after the case node expressions have been constant-folded) and subsequently storing it in a boolean field.

Thanks,
  Attila.