Remove always-true --harmony-json-stringify runtime flag

It shipped in Chrome 72.

Bug: v8:7782
Change-Id: I9ddee4370dd65821020dd7292d9e9b9850d060df
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1581603Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60985}

src/bootstrapper.cc

@@ -4158,7 +4158,6 @@ EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_class_fields)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_dynamic_import)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_import_meta)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_numeric_separator)
-EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_json_stringify)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_regexp_sequence)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_await_optimization)
 EMPTY_INITIALIZE_GLOBAL_FOR_FEATURE(harmony_hashbang)

src/flag-definitions.h

@@ -247,7 +247,6 @@ DEFINE_IMPLICATION(harmony_private_methods, harmony_private_fields)
   V(harmony_import_meta, "harmony import.meta property")                       \
   V(harmony_dynamic_import, "harmony dynamic import")                          \
   V(harmony_global, "harmony global")                                          \
-  V(harmony_json_stringify, "well-formed JSON.stringify")                      \
   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")              \

src/json-stringifier.cc

@@ -883,7 +883,7 @@ void JsonStringifier::SerializeStringUnchecked_(
     SrcChar c = src[i];
     if (DoNotEscape(c)) {
       dest->Append(c);
-    } else if (FLAG_harmony_json_stringify && c >= 0xD800 && c <= 0xDFFF) {
+    } else if (c >= 0xD800 && c <= 0xDFFF) {
       // The current character is a surrogate.
       if (c <= 0xDBFF) {
         // The current character is a leading surrogate.
@@ -946,7 +946,7 @@ void JsonStringifier::SerializeString_(Handle<String> string) {
       SrcChar c = reader.Get<SrcChar>(i);
       if (DoNotEscape(c)) {
         builder_.Append<SrcChar, DestChar>(c);
-      } else if (FLAG_harmony_json_stringify && c >= 0xD800 && c <= 0xDFFF) {
+      } else if (c >= 0xD800 && c <= 0xDFFF) {
         // The current character is a surrogate.
         if (c <= 0xDBFF) {
           // The current character is a leading surrogate.
@@ -1002,8 +1002,7 @@ bool JsonStringifier::DoNotEscape(uint8_t c) {
 template <>
 bool JsonStringifier::DoNotEscape(uint16_t c) {
   // https://tc39.github.io/ecma262/#table-json-single-character-escapes
-  return c >= 0x23 && c != 0x5C && c != 0x7F &&
-         (!FLAG_harmony_json_stringify || (c < 0xD800 || c > 0xDFFF));
+  return c >= 0x23 && c != 0x5C && c != 0x7F && (c < 0xD800 || c > 0xDFFF);
 }
 
 void JsonStringifier::NewLine() {

test/cctest/test-strings.cc

@@ -1228,7 +1228,6 @@ TEST(JSONStringifySliceMadeExternal) {
 }
 
 TEST(JSONStringifyWellFormed) {
-  FLAG_harmony_json_stringify = true;
   CcTest::InitializeVM();
   v8::HandleScope handle_scope(CcTest::isolate());
   v8::Local<v8::Context> context = CcTest::isolate()->GetCurrentContext();

test/mjsunit/harmony/well-formed-json-stringify-checked.js

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-json-stringify
-
 // Test JSON.stringify for cases that hit
 // JsonStringifier::SerializeString_.
 

test/mjsunit/harmony/well-formed-json-stringify-unchecked.js

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --harmony-json-stringify
-
 // Test JSON.stringify for cases that hit
 // JsonStringifier::SerializeStringUnchecked_.
 

test/test262/testcfg.py

@@ -56,7 +56,6 @@ FEATURE_FLAGS = {
   'Intl.Segmenter': '--harmony-intl-segmenter',
   'Symbol.prototype.description': '--harmony-symbol-description',
   'globalThis': '--harmony-global',
-  'well-formed-json-stringify': '--harmony-json-stringify',
   'export-star-as-namespace-from-module': '--harmony-namespace-exports',
   'Object.fromEntries': '--harmony-object-from-entries',
   'hashbang': '--harmony-hashbang',