Pipeline layout incorrectly indexes into a root table array
when there are more root descriptors than root tables.
To fix, the array is dynamically sized where parameters
are appended instead of indexed into the root signature.
Bug: dawn:449
Change-Id: I6d7f65fb791d323704b1c3a3af9c871a79e32a30
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/22960
Commit-Queue: Bryan Bernhart <bryan.bernhart@intel.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
