8040213: C2 does not put all modified nodes on IGVN worklist
Summary: Verification code is added that checks if modified nodes are put on the IGVN worklist and modified nodes are processed by 'PhaseIterGVN::transform_old()'
Reviewed-by: kvn, jrose
^build/
^dist/
/nbproject/private/
^src/share/tools/hsdis/build/
^src/share/tools/IdealGraphVisualizer/[a-zA-Z0-9]*/build/
^src/share/tools/IdealGraphVisualizer/build/
^src/share/tools/IdealGraphVisualizer/dist/
^.hgtip
.DS_Store