Revert r338222 "[DAGCombiner] Remove unnecessary calls to AddToWorklist."
Revert r338222 "[DAGCombiner] Remove unnecessary calls to AddToWorklist."

Thinking about it more it might be possible for the later nodes to be folded in getNode in such a way that the other created nodes are left dead. This can cause use counts to be incorrect on nodes that aren't dead.

So its probably safer to leave this alone.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@338298 91177308-0d34-0410-b5e6-96231b3b80d8

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