Ship Array.prototype.{flat,flatMap} 🎉

Intent to ship:
https://groups.google.com/d/msg/v8-users/15GL4-UHEcE/OEKOou3bBgAJ

Bug: v8:7220
Change-Id: Ib1efde29e27b956db3d8ebf12ff7a3f163db7c22
Reviewed-on: https://chromium-review.googlesource.com/1076335Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53419}

src/debug/debug-evaluate.cc

@@ -632,6 +632,8 @@ SharedFunctionInfo::SideEffectState BuiltinGetSideEffectState(
     case Builtins::kArrayPrototypeEntries:
     case Builtins::kArrayPrototypeFind:
     case Builtins::kArrayPrototypeFindIndex:
+    case Builtins::kArrayPrototypeFlat:
+    case Builtins::kArrayPrototypeFlatMap:
     case Builtins::kArrayPrototypeKeys:
     case Builtins::kArrayPrototypeSlice:
     case Builtins::kArrayForEach:

src/flag-definitions.h

@@ -226,8 +226,7 @@ DEFINE_IMPLICATION(harmony_class_fields, harmony_private_fields)
   V(harmony_public_fields, "harmony public fields in class literals")      \
   V(harmony_private_fields, "harmony private fields in class literals")    \
   V(harmony_numeric_separator, "harmony numeric separator between digits") \
-  V(harmony_string_matchall, "harmony String.prototype.matchAll")          \
-  V(harmony_array_flat, "harmony Array.prototype.{flat,flatMap}")
+  V(harmony_string_matchall, "harmony String.prototype.matchAll")
 
 // Features that are shipping (turned on by default, but internal flag remains).
 #define HARMONY_SHIPPING(V)                                                   \
@@ -241,7 +240,8 @@ DEFINE_IMPLICATION(harmony_class_fields, harmony_private_fields)
   V(harmony_import_meta, "harmony import.meta property")                      \
   V(harmony_bigint, "harmony arbitrary precision integers")                   \
   V(harmony_dynamic_import, "harmony dynamic import")                         \
-  V(harmony_array_prototype_values, "harmony Array.prototype.values")
+  V(harmony_array_prototype_values, "harmony Array.prototype.values")         \
+  V(harmony_array_flat, "harmony Array.prototype.{flat,flatMap}")
 
 // Once a shipping feature has proved stable in the wild, it will be dropped
 // from HARMONY_SHIPPING, all occurrences of the FLAG_ variable are removed,

test/debugger/debug/side-effect/debug-evaluate-no-side-effect-builtins.js

@@ -68,8 +68,8 @@ function listener(event, exec_state, event_data, data) {
     fail(`Array.from([1, 2, 3])`);
     fail(`Array.of(1, 2, 3)`);
     var function_param = [
-      "forEach", "every", "some", "reduce", "reduceRight", "find", "filter",
-      "map", "findIndex"
+      "flatMap", "forEach", "every", "some", "reduce", "reduceRight", "find",
+      "filter", "map", "findIndex"
     ];
     var fails = ["toString", "join", "toLocaleString", "pop", "push", "reverse",
       "shift", "unshift", "splice", "sort", "copyWithin", "fill"];