Optimizes InstructionSelector::AddInputsToFrameStateDescriptor by
taking advantage of SparseInputMask data structure to more quickly
handle empty inputs and insert all the OptimizedOut entries in one go.
The number of empty inputs is now determined using CountTrailingZeros
rather than iterating over them one at a time.

Gives a 9% improvement to SelectInstructions runtime call stat for
Octane in turboprop.

Bug: v8:10051
Change-Id: Ib13d6f9644b4c89ba0546a19fe0ed623d69fec99
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2037443
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66591}