[nowasm] Fix compilation

This fixes a compile error in no-wasm / jitless builds introduced in
https://crrev.com/c/2912779.

R=neis@chromium.org
CC=manoskouk@chromium.org

Cq-Include-Trybots: luci.v8.try:v8_linux64_no_wasm_compile_rel
Cq-Include-Trybots: luci.v8.try:v8_linux_arm_lite_rel_ng
Change-Id: Ia256679dba5093b30821859376aba81b4900efed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2919829Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74787}

src/compiler/pipeline.cc

@@ -2048,6 +2048,7 @@ struct ScheduledEffectControlLinearizationPhase {
   }
 };
 
+#if V8_ENABLE_WEBASSEMBLY
 struct WasmOptimizationPhase {
   DECL_PIPELINE_PHASE_CONSTANTS(WasmOptimization)
 
@@ -2104,6 +2105,7 @@ struct WasmOptimizationPhase {
     }
   }
 };
+#endif  // V8_ENABLE_WEBASSEMBLY
 
 struct CsaEarlyOptimizationPhase {
   DECL_PIPELINE_PHASE_CONSTANTS(CSAEarlyOptimization)