[tint] Remove duplicate lowering

This was likely added in the atomic vec2u change.

Change-Id: Ib6475e8529575b9a0b8250fc84ae31ced4b6acf9
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/298695
Commit-Queue: Peter McNeeley <petermcneeley@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>

src/tint/lang/wgsl/reader/reader.cc

diff --git a/src/tint/lang/wgsl/reader/reader.cc b/src/tint/lang/wgsl/reader/reader.cc
index 4147ce5..cfe7a1f 100644
--- a/src/tint/lang/wgsl/reader/reader.cc
+++ b/src/tint/lang/wgsl/reader/reader.cc
@@ -76,7 +76,6 @@
         }
     }
     // Lower from WGSL-dialect to core-dialect
-    auto res = Lower(ir);
     TINT_CHECK_RESULT(Lower(ir));
 
     return ir;