LibJS: Make parse_temporal_instant() take a StringView

The underlying parse_temporal_instant_string() function already does
this as well.

Userland/Libraries/LibJS/Runtime/Temporal/Instant.cpp

@@ -100,7 +100,7 @@ ThrowCompletionOr<Instant*> to_temporal_instant(VM& vm, Value item)
     }
 
     // 2. Let string be ? ToString(item).
-    auto string = TRY(item.to_deprecated_string(vm));
+    auto string = TRY(item.to_string(vm));
 
     // 3. Let epochNanoseconds be ? ParseTemporalInstant(string).
     auto* epoch_nanoseconds = TRY(parse_temporal_instant(vm, string));
@@ -110,7 +110,7 @@ ThrowCompletionOr<Instant*> to_temporal_instant(VM& vm, Value item)
 }
 
 // 8.5.4 ParseTemporalInstant ( isoString ), https://tc39.es/proposal-temporal/#sec-temporal-parsetemporalinstant
-ThrowCompletionOr<BigInt*> parse_temporal_instant(VM& vm, DeprecatedString const& iso_string)
+ThrowCompletionOr<BigInt*> parse_temporal_instant(VM& vm, StringView iso_string)
 {
     // 1. Assert: Type(isoString) is String.
 

Userland/Libraries/LibJS/Runtime/Temporal/Instant.h

@@ -45,7 +45,7 @@ bool is_valid_epoch_nanoseconds(BigInt const& epoch_nanoseconds);
 bool is_valid_epoch_nanoseconds(Crypto::SignedBigInteger const& epoch_nanoseconds);
 ThrowCompletionOr<Instant*> create_temporal_instant(VM&, BigInt const& nanoseconds, FunctionObject const* new_target = nullptr);
 ThrowCompletionOr<Instant*> to_temporal_instant(VM&, Value item);
-ThrowCompletionOr<BigInt*> parse_temporal_instant(VM&, DeprecatedString const& iso_string);
+ThrowCompletionOr<BigInt*> parse_temporal_instant(VM&, StringView iso_string);
 i32 compare_epoch_nanoseconds(BigInt const&, BigInt const&);
 ThrowCompletionOr<BigInt*> add_instant(VM&, BigInt const& epoch_nanoseconds, double hours, double minutes, double seconds, double milliseconds, double microseconds, double nanoseconds);
 BigInt* difference_instant(VM&, BigInt const& nanoseconds1, BigInt const& nanoseconds2, u64 rounding_increment, StringView smallest_unit, StringView rounding_mode);