[rab/gsab] Temporarily stage --harmony-rab-gsab to enable fuzzing

Please revert this CL if it causes any trouble!

Bug: v8:11111
Change-Id: I6061fdc0aed82952f093ede9ecd252be1ac99519
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3528495Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79499}

src/flags/flag-definitions.h

@@ -302,8 +302,6 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
   V(harmony_weak_refs_with_cleanup_some,                                       \
     "harmony weak references with FinalizationRegistry.prototype.cleanupSome") \
   V(harmony_import_assertions, "harmony import assertions")                    \
-  V(harmony_rab_gsab,                                                          \
-    "harmony ResizableArrayBuffer / GrowableSharedArrayBuffer")                \
   V(harmony_temporal, "Temporal")                                              \
   V(harmony_shadow_realm, "harmony ShadowRealm")                               \
   V(harmony_struct, "harmony structs and shared structs")
@@ -317,8 +315,11 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
 #endif
 
 // Features that are complete (but still behind the --harmony flag).
+// --harmony-rab-gsab is staged temporarily to enable fuzzing.
 #define HARMONY_STAGED_BASE(V)                        \
-  V(harmony_array_grouping, "harmony array grouping")
+  V(harmony_array_grouping, "harmony array grouping") \
+  V(harmony_rab_gsab,                                 \
+    "harmony ResizableArrayBuffer / GrowableSharedArrayBuffer")
 
 #ifdef V8_INTL_SUPPORT
 #define HARMONY_STAGED(V) \