Replace the struct type of binary and symbol parameter nodes with a
lookup of the struct type in the tree.

Bug: angleproject:2494
Change-Id: I1e892e0f1b1f97302d1cdce1035f51c01d0efd9e
Reviewed-on: https://chromium-review.googlesource.com/1135695Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>