[ubsan][arm64] Fixed a left shift of negative value error

This is similar to the change made to IsImmLSPair in
9f7ae50a.

Change-Id: I17a7cc95661542efb5711df0639cc11ac7926702
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1971950
Commit-Queue: Joey Gouly <joey.gouly@arm.com>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65501}

src/codegen/arm64/assembler-arm64-inl.h

@@ -1013,7 +1013,8 @@ Instr Assembler::ImmLS(int imm9) {
 }
 
 Instr Assembler::ImmLSPair(int imm7, unsigned size) {
-  DCHECK_EQ((imm7 >> size) << size, imm7);
+  DCHECK_EQ(imm7,
+            static_cast<int>(static_cast<uint32_t>(imm7 >> size) << size));
   int scaled_imm7 = imm7 >> size;
   DCHECK(is_int7(scaled_imm7));
   return truncate_to_int7(scaled_imm7) << ImmLSPair_offset;