Revert "Avoid UTF8 conversion in JSNumberFormat"

This reverts commit f70e5abf.

Reason for revert: Arm64 build breakage: https://ci.chromium.org/p/v8/builders/ci/V8%20Android%20Arm64%20-%20builder/30710

Original change's description:
> Avoid UTF8 conversion in JSNumberFormat
> 
> Change-Id: Idf4e95e6979adfbca24f8fd213967f821a136d87
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2057930
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Commit-Queue: Frank Tang <ftang@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66353}

TBR=jkummerow@chromium.org,ftang@chromium.org

Change-Id: I01300a6eec5cb3f2e97da74744328d58d9e51d14
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2062742Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66354}

src/objects/js-number-format.cc

@@ -353,26 +353,28 @@ bool UseGroupingFromSkeleton(const icu::UnicodeString& skeleton) {
 
 // Parse currency code from skeleton. For example, skeleton as
 // "currency/TWD .00 rounding-mode-half-up unit-width-full-name;"
-const icu::UnicodeString CurrencyFromSkeleton(
-    const icu::UnicodeString& skeleton) {
-  const char currency[] = "currency/";
-  int32_t index = skeleton.indexOf(currency);
-  if (index < 0) return "";
-  return skeleton.tempSubString(index + std::strlen(currency), 3);
+std::string CurrencyFromSkeleton(const icu::UnicodeString& skeleton) {
+  std::string str;
+  str = skeleton.toUTF8String<std::string>(str);
+  std::string search("currency/");
+  size_t index = str.find(search);
+  if (index == str.npos) return "";
+  return str.substr(index + search.size(), 3);
 }
 
-const icu::UnicodeString NumberingSystemFromSkeleton(
-    const icu::UnicodeString& skeleton) {
-  int32_t index = skeleton.indexOf("latin");
-  if (index >= 0) return "latn";
-  const char numbering_system[] = "numbering-system/";
-  index = skeleton.indexOf(numbering_system);
-  if (index < 0) return "";
-  const icu::UnicodeString res =
-      skeleton.tempSubString(index + std::strlen(numbering_system));
-  index = res.indexOf(" ");
-  if (index < 0) return res;
-  return res.tempSubString(0, index);
+std::string NumberingSystemFromSkeleton(const icu::UnicodeString& skeleton) {
+  std::string str;
+  str = skeleton.toUTF8String<std::string>(str);
+  size_t index = str.find("latin");
+  if (index != str.npos) return "latn";
+  std::string search("numbering-system/");
+  index = str.find(search);
+  if (index == str.npos) return "";
+  size_t space_index = str.find(" ", index + search.size());
+  if (space_index != str.npos) {
+    space_index -= index + search.size();
+  }
+  return str.substr(index + search.size(), space_index);
 }
 
 // Return CurrencySign as string based on skeleton.
@@ -687,8 +689,7 @@ Handle<JSObject> JSNumberFormat::ResolvedOptions(
   Handle<JSObject> options = factory->NewJSObject(isolate->object_function());
 
   Handle<String> locale = Handle<String>(number_format->locale(), isolate);
-  const icu::UnicodeString numberingSystem_ustr =
-      NumberingSystemFromSkeleton(skeleton);
+  std::string numberingSystem = NumberingSystemFromSkeleton(skeleton);
   // 5. For each row of Table 4, except the header row, in table order, do
   // Table 4: Resolved Options of NumberFormat Instances
   //  Internal Slot                    Property
@@ -707,25 +708,22 @@ Handle<JSObject> JSNumberFormat::ResolvedOptions(
                                        factory->locale_string(), locale,
                                        Just(kDontThrow))
             .FromJust());
-  Handle<String> numberingSystem_string;
-  CHECK(Intl::ToString(isolate, numberingSystem_ustr)
-            .ToHandle(&numberingSystem_string));
-  CHECK(JSReceiver::CreateDataProperty(isolate, options,
-                                       factory->numberingSystem_string(),
-                                       numberingSystem_string, Just(kDontThrow))
+  CHECK(JSReceiver::CreateDataProperty(
+            isolate, options, factory->numberingSystem_string(),
+            factory->NewStringFromAsciiChecked(numberingSystem.c_str()),
+            Just(kDontThrow))
             .FromJust());
   Style style = StyleFromSkeleton(skeleton);
   CHECK(JSReceiver::CreateDataProperty(
             isolate, options, factory->style_string(),
             StyleAsString(isolate, style), Just(kDontThrow))
             .FromJust());
-  const icu::UnicodeString currency_ustr = CurrencyFromSkeleton(skeleton);
-  if (!currency_ustr.isEmpty()) {
-    Handle<String> currency_string;
-    CHECK(Intl::ToString(isolate, currency_ustr).ToHandle(&currency_string));
-    CHECK(JSReceiver::CreateDataProperty(isolate, options,
-                                         factory->currency_string(),
-                                         currency_string, Just(kDontThrow))
+  std::string currency = CurrencyFromSkeleton(skeleton);
+  if (!currency.empty()) {
+    CHECK(JSReceiver::CreateDataProperty(
+              isolate, options, factory->currency_string(),
+              factory->NewStringFromAsciiChecked(currency.c_str()),
+              Just(kDontThrow))
               .FromJust());
 
     CHECK(JSReceiver::CreateDataProperty(