[ESNext] Stage Promise.allSettled

Bug: v8:9060
Change-Id: Ibea24457354a6b7d32449ae41c680ff37481341e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1565541Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60835}

src/flag-definitions.h

@@ -217,8 +217,7 @@ DEFINE_IMPLICATION(harmony_private_methods, harmony_private_fields)
   V(harmony_class_fields, "harmony fields in class literals")             \
   V(harmony_private_methods, "harmony private methods in class literals") \
   V(harmony_regexp_sequence, "RegExp Unicode sequence properties")        \
-  V(harmony_weak_refs, "harmony weak references")                         \
-  V(harmony_promise_all_settled, "harmony Promise.allSettled")
+  V(harmony_weak_refs, "harmony weak references")
 
 #ifdef V8_INTL_SUPPORT
 #define HARMONY_INPROGRESS(V)                                              \
@@ -229,7 +228,8 @@ DEFINE_IMPLICATION(harmony_private_methods, harmony_private_fields)
 #endif
 
 // Features that are complete (but still behind --harmony/es-staging flag).
-#define HARMONY_STAGED_BASE(V)
+#define HARMONY_STAGED_BASE(V) \
+  V(harmony_promise_all_settled, "harmony Promise.allSettled")
 
 #ifdef V8_INTL_SUPPORT
 #define HARMONY_STAGED(V)                                                  \