Enable DFS traversal to Constant Propagation
Enable DFS traversal to Constant Propagation

Summary: I have been propagating constant in a very conservative way, which means I only propagate to the next block if it's the only successive block. In this diff, I activated DFS traversal to enable constant propagation in deeper level.

Reviewed By: bertmaher

Differential Revision: D3545569

fbshipit-source-id: aeafc64f50f9977ec4b3a6e57623ac62c137178c

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