fixed unit tests so that they pass when assertions are disabled
NodeRefIterator advances lazily instead of eagerly, allowing the next element to be cached in the advance operation
NodeClassIterator advances lazily instead of eagerly, allowing the next element to be cached in the advance operation
re-enabled use of generated Nodes
Remove redundant Begin nodes before LoopExit.

--HG--
extra : rebase_source : d98c000df8da4dc12cc211e9332e6914e1725440
extra : amend_source : e25cab88776aa79957467794a52093e77da09895
Split method in OptimizingLinearScanWalker.

--HG--
extra : rebase_source : e4cb776ef610d30080de08cd5052b968f16e2793
Disable use of generated Nodes.

--HG--
extra : rebase_source : 69238b00893242b4de192a1df80fa6c3533b6f49
Truffle: fixed potential non determinism in the invalidation of inlining.
projects must be rebuilt when any of their dependencies are rebuilt
improved javadoc for NodeClass.is()
mx: added ctw command to simplify executing CompileTheWorld