LibJS: Make string_to_number() return double instead of Optional<Value>

This would never return an empty optional or non-numeric value, and in
fact every caller as_double()'d the value right away.
Let's make the type match reality instead :^)

Userland/Libraries/LibJS/Runtime/Date.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2022, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2020-2023, Linus Groh <linusg@serenityos.org>
  * Copyright (c) 2022, Tim Flynn <trflynn89@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
@@ -570,7 +570,7 @@ double parse_time_zone_offset_string(StringView offset_string)
     auto parsed_hours = *parse_result->time_zone_utc_offset_hour;
 
     // 10. Let hours be ℝ(StringToNumber(CodePointsToString(parsedHours))).
-    auto hours = string_to_number(parsed_hours)->as_double();
+    auto hours = string_to_number(parsed_hours);
 
     double minutes { 0 };
     double seconds { 0 };
@@ -587,7 +587,7 @@ double parse_time_zone_offset_string(StringView offset_string)
         auto parsed_minutes = *parse_result->time_zone_utc_offset_minute;
 
         // b. Let minutes be ℝ(StringToNumber(CodePointsToString(parsedMinutes))).
-        minutes = string_to_number(parsed_minutes)->as_double();
+        minutes = string_to_number(parsed_minutes);
     }
 
     // 13. If parseResult does not contain two MinuteSecond Parse Nodes, then
@@ -601,7 +601,7 @@ double parse_time_zone_offset_string(StringView offset_string)
         auto parsed_seconds = *parse_result->time_zone_utc_offset_second;
 
         // b. Let seconds be ℝ(StringToNumber(CodePointsToString(parsedSeconds))).
-        seconds = string_to_number(parsed_seconds)->as_double();
+        seconds = string_to_number(parsed_seconds);
     }
 
     // 15. If parseResult does not contain a TemporalDecimalFraction Parse Node, then
@@ -621,7 +621,7 @@ double parse_time_zone_offset_string(StringView offset_string)
         auto nanoseconds_string = fraction.substring_view(1, 9);
 
         // d. Let nanoseconds be ℝ(StringToNumber(nanosecondsString)).
-        nanoseconds = string_to_number(nanoseconds_string)->as_double();
+        nanoseconds = string_to_number(nanoseconds_string);
     }
 
     // 17. Return sign × (((hours × 60 + minutes) × 60 + seconds) × 10^9 + nanoseconds).

Userland/Libraries/LibJS/Runtime/Value.cpp

@@ -664,36 +664,36 @@ static Optional<NumberParseResult> parse_number_text(StringView text)
 }
 
 // 7.1.4.1.1 StringToNumber ( str ), https://tc39.es/ecma262/#sec-stringtonumber
-Optional<Value> string_to_number(StringView string)
+double string_to_number(StringView string)
 {
     // 1. Let text be StringToCodePoints(str).
     DeprecatedString text = Utf8View(string).trim(whitespace_characters, AK::TrimMode::Both).as_string();
 
     // 2. Let literal be ParseText(text, StringNumericLiteral).
     if (text.is_empty())
-        return Value(0);
+        return 0;
     if (text == "Infinity" || text == "+Infinity")
-        return js_infinity();
+        return INFINITY;
     if (text == "-Infinity")
-        return js_negative_infinity();
+        return -INFINITY;
 
     auto result = parse_number_text(text);
 
     // 3. If literal is a List of errors, return NaN.
     if (!result.has_value())
-        return js_nan();
+        return NAN;
 
     // 4. Return StringNumericValue of literal.
     if (result->base != 10) {
         auto bigint = Crypto::UnsignedBigInteger::from_base(result->base, result->literal);
-        return Value(bigint.to_double());
+        return bigint.to_double();
     }
 
     auto maybe_double = text.to_double(AK::TrimWhitespace::No);
     if (!maybe_double.has_value())
-        return js_nan();
+        return NAN;
 
-    return Value(*maybe_double);
+    return *maybe_double;
 }
 
 // 7.1.4 ToNumber ( argument ), https://tc39.es/ecma262/#sec-tonumber

Userland/Libraries/LibJS/Runtime/Value.h

@@ -563,7 +563,7 @@ enum class NumberToStringMode {
 };
 ErrorOr<String> number_to_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
 DeprecatedString number_to_deprecated_string(double, NumberToStringMode = NumberToStringMode::WithExponent);
-Optional<Value> string_to_number(StringView);
+double string_to_number(StringView);
 
 inline bool Value::operator==(Value const& value) const { return same_value(*this, value); }