Simplify interface block instance recording Instead of storing instance names as part of TInterfaceBlock, store instance names only in interface block instance symbols. Wherever the instance name is needed it can be fetched from the instance symbol. BUG=angleproject:2267 TEST=angle_end2end_tests Change-Id: Ia265e4db7901eebec57c9c3769d84c17651a35ba Reviewed-on: https://chromium-review.googlesource.com/803221 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>