Revert "[regexp] Stage match indices."

This reverts commit bd9efe1f.

Reason for revert: clusterfuzz
Bug: chromium:1029174

Original change's description:
> [regexp] Stage match indices.
> 
> Bug: v8:9548
> Change-Id: Id6be43433b12733e39db712559715ba30e681059
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1935207
> Commit-Queue: Joshua Litt <joshualitt@chromium.org>
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65218}

TBR=adamk@chromium.org,jgruber@chromium.org,joshualitt@chromium.org

Change-Id: I098385e2dcebc7bfacd91312bcebfdb889b3d0ca
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:9548
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1941137Reviewed-by: Joshua Litt <joshualitt@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65222}

src/flags/flag-definitions.h

@@ -207,6 +207,7 @@ DEFINE_IMPLICATION(harmony_import_meta, harmony_dynamic_import)
   V(harmony_string_replaceall, "harmony String.prototype.replaceAll") \
   V(harmony_regexp_sequence, "RegExp Unicode sequence properties")    \
   V(harmony_weak_refs, "harmony weak references")                     \
+  V(harmony_regexp_match_indices, "harmony regexp match indices")     \
   V(harmony_top_level_await, "harmony top level await")
 
 #ifdef V8_INTL_SUPPORT
@@ -218,8 +219,7 @@ DEFINE_IMPLICATION(harmony_import_meta, harmony_dynamic_import)
 #endif
 
 // Features that are complete (but still behind --harmony/es-staging flag).
-#define HARMONY_STAGED_BASE(V)                                    \
-  V(harmony_regexp_match_indices, "harmony regexp match indices") \
+#define HARMONY_STAGED_BASE(V)                                     \
   V(harmony_private_methods, "harmony private methods in class literals")
 
 #ifdef V8_INTL_SUPPORT