[intl] Stage Intl.DisplayNames v2

Stage 3 proposal
Spec: https://tc39.es/intl-displaynames-v2/
R2T: https://groups.google.com/a/chromium.org/g/blink-dev/c/XOJE7zVlxnI/m/cnkuazxHAwAJ
Design Doc: https://docs.google.com/document/d/17hQz4nOC7PJYhxc_MU-BRoT6BnYGZv66XlU1iGX0ywQ

Bug: v8:11637
Change-Id: I6183f53bd7c3eae174c306debf0779a5be051d29
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2952040Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75089}

src/flags/flag-definitions.h

@@ -278,9 +278,7 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
     "harmony ResizableArrayBuffer / GrowableSharedArrayBuffer")
 
 #ifdef V8_INTL_SUPPORT
-#define HARMONY_INPROGRESS(V) \
-  HARMONY_INPROGRESS_BASE(V)  \
-  V(harmony_intl_displaynames_v2, "Intl.DisplayNames v2")
+#define HARMONY_INPROGRESS(V) HARMONY_INPROGRESS_BASE(V)
 #else
 #define HARMONY_INPROGRESS(V) HARMONY_INPROGRESS_BASE(V)
 #endif
@@ -294,6 +292,7 @@ DEFINE_BOOL(harmony_shipping, true, "enable all shipped harmony features")
 #define HARMONY_STAGED(V)                                 \
   HARMONY_STAGED_BASE(V)                                  \
   V(harmony_intl_best_fit_matcher, "Intl BestFitMatcher") \
+  V(harmony_intl_displaynames_v2, "Intl.DisplayNames v2") \
   V(harmony_intl_locale_info, "Intl locale info")         \
   V(harmony_intl_more_timezone,                           \
     "Extend Intl.DateTimeFormat timeZoneName Option")