[Temporal] Use MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE

1. Move the use of MAYBE_RETURN to MAYBE_ASSIGN_RETURN_ON_EXCEPTION_VALUE
if possible.
2. Remove some MYABE_RETURN in the wrong spot and therefore fix some tests.
3. Change Intl::GetTimeZoneIndex() to return Maybe<int32_t> as index and use
< 0 value to indicate not getting index to make the function signature
simpler.

Bug: v8:11544
Change-Id: I685cbff142e9dea69ef316a1bc180730aef5aec8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3625839Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80379}

src/objects/intl-objects.cc

@@ -2861,18 +2861,16 @@ std::string Intl::TimeZoneIdFromIndex(int32_t index) {
   return id;
 }
 
-Maybe<bool> Intl::GetTimeZoneIndex(Isolate* isolate, Handle<String> identifier,
-                                   int32_t* index) {
+int32_t Intl::GetTimeZoneIndex(Isolate* isolate, Handle<String> identifier) {
   if (identifier->Equals(*isolate->factory()->UTC_string())) {
-    *index = 0;
-    return Just(true);
+    return 0;
   }
 
   std::string identifier_str(identifier->ToCString().get());
   std::unique_ptr<icu::TimeZone> tz(
       icu::TimeZone::createTimeZone(identifier_str.c_str()));
   if (!IsValidTimeZoneName(*tz)) {
-    return Just(false);
+    return -1;
   }
 
   std::unique_ptr<icu::StringEnumeration> enumeration(
@@ -2883,11 +2881,10 @@ Maybe<bool> Intl::GetTimeZoneIndex(Isolate* isolate, Handle<String> identifier,
   UErrorCode status = U_ZERO_ERROR;
   while (U_SUCCESS(status) &&
          (id = enumeration->next(nullptr, status)) != nullptr) {
+    curr++;
     if (identifier_str == id) {
-      *index = curr + 1;
-      return Just(true);
+      return curr;
     }
-    curr++;
   }
   CHECK(U_SUCCESS(status));
   // We should not reach here, the !IsValidTimeZoneName should return earlier

src/objects/intl-objects.h

@@ -356,8 +356,10 @@ class Intl {
   // Function to support Temporal
   V8_WARN_UNUSED_RESULT static std::string TimeZoneIdFromIndex(int32_t index);
 
-  V8_WARN_UNUSED_RESULT static Maybe<bool> GetTimeZoneIndex(
-      Isolate* isolate, Handle<String> identifier, int32_t* index);
+  // Return the index of timezone which later could be used with
+  // TimeZoneIdFromIndex. Returns -1 while the identifier is not a built-in
+  // TimeZone name.
+  static int32_t GetTimeZoneIndex(Isolate* isolate, Handle<String> identifier);
 
   V8_WARN_UNUSED_RESULT static MaybeHandle<String> CanonicalizeTimeZoneName(
       Isolate* isolate, Handle<String> identifier);