[compiler] Make aseemgarg owner of simd-scalar-lowering.*

Aseem is the main auther of simd-scalar-lowering and should therefore be
able to lgtm changes to that file.

No-Try: true
No-Tree-Checks: true

R=titzer@chromium.org
CC=aseemgarg@chromium.org

Change-Id: If62d895fb18e8fd59735fec63faa38ca7a6598c5
Reviewed-on: https://chromium-review.googlesource.com/1070984Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53342}

src/compiler/OWNERS

@@ -22,4 +22,6 @@ per-file wasm-*=kschimpf@chromium.org
 
 per-file int64-lowering.*=ahaas@chromium.org
 
+per-file simd-scalar-lowering.*=aseemgarg@chromium.org
+
 # COMPONENT: Blink>JavaScript>Compiler