[turbofan] Fix missing operators for JSGlobalSpecialization::Flags.

R=jarin@chromium.org
BUG=v8:4470
LOG=n

Review URL: https://codereview.chromium.org/1394753002

Cr-Commit-Position: refs/heads/master@{#31170}

src/compiler/js-global-specialization.h

@@ -75,6 +75,8 @@ class JSGlobalSpecialization final : public AdvancedReducer {
   DISALLOW_COPY_AND_ASSIGN(JSGlobalSpecialization);
 };
 
+DEFINE_OPERATORS_FOR_FLAGS(JSGlobalSpecialization::Flags)
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8