Fix unnecessary copy of for loop variables in ANGLE Bug: angleproject:3075 Change-Id: I34dd5d4ecded6def5a2b46369277312af0de7c8c Reviewed-on: https://chromium-review.googlesource.com/c/1443572 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>