[intl] Store resolveLocale on the context

This unblocks new feature work that require this operation from C++,
whilst the porting to C++ is underway.

Bug: v8:5751
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Icb7f05bbea42ecfa1abc3cefb6d1bf8542ed921b
Reviewed-on: https://chromium-review.googlesource.com/1127082
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54265}

src/contexts.h

@@ -96,6 +96,7 @@ enum ContextLookupFlags {
   V(PROMISE_FUNCTION_INDEX, JSFunction, promise_function)                 \
   V(RANGE_ERROR_FUNCTION_INDEX, JSFunction, range_error_function)         \
   V(REFERENCE_ERROR_FUNCTION_INDEX, JSFunction, reference_error_function) \
+  V(RESOLVE_LOCALE_FUNCTION_INDEX, JSFunction, resolve_locale)            \
   V(SET_ADD_INDEX, JSFunction, set_add)                                   \
   V(SET_DELETE_INDEX, JSFunction, set_delete)                             \
   V(SET_HAS_INDEX, JSFunction, set_has)                                   \

src/js/intl.js

@@ -415,6 +415,9 @@ function resolveLocale(service, requestedLocales, options) {
   return resolved;
 }
 
+%InstallToContext([
+  "resolve_locale", resolveLocale
+]);
 
 /**
  * Look up the longest non-empty prefix of |locale| that is an element of

src/objects/intl-objects.cc

@@ -1237,6 +1237,29 @@ MaybeHandle<JSReceiver> Intl::UnwrapReceiver(Isolate* isolate,
   return Handle<JSReceiver>::cast(new_receiver);
 }
 
+// TODO(bstell): Convert this to C++ instead of calling out to the
+// JS implementation.
+MaybeHandle<JSObject> Intl::ResolveLocale(Isolate* isolate, const char* service,
+                                          Handle<Object> requestedLocales,
+                                          Handle<Object> options) {
+  Handle<String> service_str =
+      isolate->factory()->NewStringFromAsciiChecked(service);
+
+  Handle<JSFunction> resolve_locale_function = isolate->resolve_locale();
+
+  Handle<Object> result;
+  Handle<Object> undefined_value(ReadOnlyRoots(isolate).undefined_value(),
+                                 isolate);
+  Handle<Object> args[] = {service_str, requestedLocales, options};
+  ASSIGN_RETURN_ON_EXCEPTION(
+      isolate, result,
+      Execution::Call(isolate, resolve_locale_function, undefined_value,
+                      arraysize(args), args),
+      JSObject);
+
+  return Handle<JSObject>::cast(result);
+}
+
 Maybe<bool> Intl::GetStringOption(Isolate* isolate, Handle<JSReceiver> options,
                                   const char* property,
                                   std::vector<const char*> values,

src/objects/intl-objects.h

@@ -201,12 +201,30 @@ class Intl {
   // Returns the underlying Intl receiver for various methods which
   // implement ECMA-402 v1 semantics for supporting initializing
   // existing Intl objects.
-  static MaybeHandle<JSReceiver> UnwrapReceiver(
+  V8_WARN_UNUSED_RESULT static MaybeHandle<JSReceiver> UnwrapReceiver(
       Isolate* isolate, Handle<JSReceiver> receiver,
       Handle<JSFunction> constructor, Intl::Type type,
       Handle<String> method_name /* TODO(gsathya): Make this char const* */,
       bool check_legacy_constructor = false);
 
+  // The ResolveLocale abstract operation compares a BCP 47 language
+  // priority list requestedLocales against the locales in
+  // availableLocales and determines the best available language to
+  // meet the request. availableLocales, requestedLocales, and
+  // relevantExtensionKeys must be provided as List values, options
+  // and localeData as Records.
+  //
+  // #ecma402/sec-partitiondatetimepattern
+  //
+  // Returns a JSObject with two properties:
+  //   (1) locale
+  //   (2) extension
+  //
+  // To access either, use JSObject::GetDataProperty.
+  V8_WARN_UNUSED_RESULT static MaybeHandle<JSObject> ResolveLocale(
+      Isolate* isolate, const char* service, Handle<Object> requestedLocales,
+      Handle<Object> options);
+
   // ECMA402 9.2.10. GetOption( options, property, type, values, fallback)
   // ecma402/#sec-getoption
   //