8086057: Crash with "modified node is not on IGVN._worklist" when running with -XX:-SplitIfBlocks
Summary: Pre-loop Opaque1 node 'pre_opaq' should be put on the IGVN worklist after modification.
Reviewed-by: kvn
8154763: Crash with "assert(RangeCheckElimination)" if RangeCheckElimination is disabled
Summary: Disable multiversioning if range check elimination is turned off.
Reviewed-by: mcberg, kvn