[StatepointLowering] Fix a mistake in rL261336
[StatepointLowering] Fix a mistake in rL261336

The check on MFI->getObjectSize() has to be on the FrameIndex, not on
the index of the FrameIndex in AllocatedStackSlots.  Weirdly, the tests
I added in rL261336 didn't catch this.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@261347 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm