Revert "Remove always-true --harmony-object-from-entries runtime flag"

This reverts commit 98bbe37e.

Reason for revert: breaks gc_stress bot
https://ci.chromium.org/p/v8/builders/ci/V8%20Linux%20-%20gc%20stress/22113

Original change's description:
> Remove always-true --harmony-object-from-entries runtime flag
>
> It shipped in Chrome 73.
>
> Bug: v8:8021
> Change-Id: I82875829ff081ce055a0184170b15c65efca1c38
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1581647
> Commit-Queue: Mathias Bynens <mathias@chromium.org>
> Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
> Auto-Submit: Mathias Bynens <mathias@chromium.org>
> Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#60992}

TBR=gsathya@chromium.org,mathias@chromium.org

Change-Id: I812d62a7e8b70a8646e606da5f0f8812fac330c7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:8021
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1582882
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60994}

src/bootstrapper.cc

@@ -1474,8 +1474,6 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
     native_context()->set_object_keys(*object_keys);
     SimpleInstallFunction(isolate_, object_function, "entries",
                           Builtins::kObjectEntries, 1, true);
-    SimpleInstallFunction(isolate_, object_function, "fromEntries",
-                          Builtins::kObjectFromEntries, 1, false);
     SimpleInstallFunction(isolate_, object_function, "values",
                           Builtins::kObjectValues, 1, true);
 
@@ -4546,6 +4544,12 @@ void Genesis::InitializeGlobal_harmony_intl_segmenter() {
 
 #endif  // V8_INTL_SUPPORT
 
+void Genesis::InitializeGlobal_harmony_object_from_entries() {
+  if (!FLAG_harmony_object_from_entries) return;
+  SimpleInstallFunction(isolate(), isolate()->object_function(), "fromEntries",
+                        Builtins::kObjectFromEntries, 1, false);
+}
+
 Handle<JSFunction> Genesis::CreateArrayBuffer(
     Handle<String> name, ArrayBufferKind array_buffer_kind) {
   // Create the %ArrayBufferPrototype%

src/flag-definitions.h

@@ -250,6 +250,7 @@ DEFINE_IMPLICATION(harmony_private_methods, harmony_private_fields)
   V(harmony_public_fields, "harmony public instance fields in class literals") \
   V(harmony_static_fields, "harmony static fields in class literals")          \
   V(harmony_string_matchall, "harmony String.prototype.matchAll")              \
+  V(harmony_object_from_entries, "harmony Object.fromEntries()")               \
   V(harmony_await_optimization, "harmony await taking 1 tick")                 \
   V(harmony_private_fields, "harmony private fields in class literals")        \
   V(harmony_hashbang, "harmony hashbang syntax")                               \

test/mjsunit/harmony/object-fromentries.js

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Flags: --harmony-object-from-entries
+
 const fromEntries = Object.fromEntries;
 const ObjectPrototype = Object.prototype;
 const ObjectPrototypeHasOwnProperty = ObjectPrototype.hasOwnProperty;

test/mjsunit/harmony/regress/regress-912504.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --always-opt --allow-natives-syntax
+// Flags: --always-opt --harmony-object-from-entries --allow-natives-syntax
 
 function test() {
   Object.fromEntries([[]]);

test/test262/testcfg.py

@@ -57,6 +57,7 @@ FEATURE_FLAGS = {
   'Symbol.prototype.description': '--harmony-symbol-description',
   'globalThis': '--harmony-global',
   'export-star-as-namespace-from-module': '--harmony-namespace-exports',
+  'Object.fromEntries': '--harmony-object-from-entries',
   'hashbang': '--harmony-hashbang',
   'BigInt': '--harmony-intl-bigint',
 }