Reland "[replaceAll] Stage String.prototype.replaceAll."

This reverts commit 3114000a.

Reason for revert: Clusterfuzz issue should be fixed.

Original change's description:
> Revert "[replaceAll] Stage String.prototype.replaceAll."
> 
> This reverts commit 825f65d3.
> 
> Reason for revert: Clusterfuzzed
> Bug: chromium:1028475
> 
> Original change's description:
> > [replaceAll] Stage String.prototype.replaceAll.
> > 
> > Intent to ship thread:
> > https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/raep1X9R_SE
> > 
> > Bug: v8:9801
> > Change-Id: I61c559b82b4119084420ffb0a14a27774e37c760
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1930608
> > Reviewed-by: Adam Klein <adamk@chromium.org>
> > Commit-Queue: Joshua Litt <joshualitt@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#65161}
> 
> TBR=adamk@chromium.org,joshualitt@chromium.org
> 
> Change-Id: I7fa44eda475b8f421f74491e60a3131d381eb789
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: v8:9801
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1935024
> Reviewed-by: Joshua Litt <joshualitt@chromium.org>
> Commit-Queue: Joshua Litt <joshualitt@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65175}

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

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: chromium:1028475, v8:9801
Change-Id: Idb5fbd1ec38084222357aeb2d9ff05d703f10eb5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1946737Reviewed-by: Joshua Litt <joshualitt@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Joshua Litt <joshualitt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65308}

src/flags/flag-definitions.h

@@ -204,7 +204,6 @@ DEFINE_IMPLICATION(harmony_import_meta, harmony_dynamic_import)
 
 // Features that are still work in progress (behind individual flags).
 #define HARMONY_INPROGRESS_BASE(V)                                    \
-  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")     \
@@ -219,7 +218,8 @@ 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)                                     \
+#define HARMONY_STAGED_BASE(V)                                        \
+  V(harmony_string_replaceall, "harmony String.prototype.replaceAll") \
   V(harmony_private_methods, "harmony private methods in class literals")
 
 #ifdef V8_INTL_SUPPORT