Fixes an issue with MEC resources' creation command reference.
Fixes an issue with MEC resources' creation command reference.

We track at what command resources are created. Resources created before
the trace (in the MEC state) do not have a "creation command". In the past
they were associated with the first command in the trace, which has caused
some minor reporting type problems, but also later on a crash. This was
partially fixed in 21f0184e9, but together with e313301e3 caused a
regression in the pipeline view, which now was no longer properly referring
to shader resources due to the now negative creation reference.

google/agi,google/agi,google/agi,google/agi,google/agi,google/agi,google/agi,google/agi