Watch out for the following case: 1. Use expects a chain output. 2. Node is expanded into multiple target ops. 3. One of the inner node produces a chain, the outer most one doesn't.
Watch out for the following case:
1. Use expects a chain output.
2. Node is expanded into multiple target ops.
3. One of the inner node produces a chain, the outer most one doesn't.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@28209 91177308-0d34-0410-b5e6-96231b3b80d8

dslab-epfl/asap,llvm-mirror/llvm,chubbymaggie/asap,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,dslab-epfl/asap,llvm-mirror/llvm,llvm-mirror/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,apple/swift-llvm,chubbymaggie/asap,chubbymaggie/asap,chubbymaggie/asap,GPUOpen-Drivers/llvm,dslab-epfl/asap,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,chubbymaggie/asap,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,dslab-epfl/asap,llvm-mirror/llvm,apple/swift-llvm,chubbymaggie/asap