AK+Everywhere: Replace custom number parsers with fast_float

Our floating point number parser was based on the fast_float library:
https://github.com/fastfloat/fast_float

However, our implementation only supports 8-bit characters. To support
UTF-16, we will need to be able to convert char16_t-based strings to
numbers as well. This works out-of-the-box with fast_float.

We can also use fast_float for integer parsing.

Libraries/LibJS/Runtime/AbstractOperations.cpp

@@ -6,7 +6,6 @@
  */
 
 #include <AK/CharacterTypes.h>
-#include <AK/FloatingPointStringConversions.h>
 #include <AK/Function.h>
 #include <AK/Optional.h>
 #include <AK/Utf16View.h>

Libraries/LibJS/Runtime/GlobalObject.cpp

@@ -7,8 +7,8 @@
 
 #include <AK/BuiltinWrappers.h>
 #include <AK/CharacterTypes.h>
-#include <AK/FloatingPointStringConversions.h>
 #include <AK/Hex.h>
+#include <AK/StringConversions.h>
 #include <AK/UnicodeUtils.h>
 #include <AK/Utf16View.h>
 #include <AK/Utf8View.h>
@@ -269,12 +269,10 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_float)
     // 6. Assert: parsedNumber is a Parse Node.
     // 7. Return StringNumericValue of parsedNumber.
     auto trimmed_string_view = trimmed_string.bytes_as_string_view();
-    auto const* begin = trimmed_string_view.characters_without_null_termination();
-    auto const* end = begin + trimmed_string_view.length();
 
-    auto parsed_number = parse_first_floating_point<double>(begin, end);
-    if (parsed_number.parsed_value())
-        return parsed_number.value;
+    auto parsed_number = AK::parse_first_number<double>(trimmed_string_view, TrimWhitespace::No);
+    if (parsed_number.has_value())
+        return parsed_number->value;
 
     auto first_code_point = *trimmed_string.code_points().begin();
     if (first_code_point == '-' || first_code_point == '+')

Libraries/LibJS/Runtime/Uint8Array.cpp

@@ -5,6 +5,7 @@
  */
 
 #include <AK/StringBuilder.h>
+#include <AK/StringConversions.h>
 #include <AK/StringUtils.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/TypedArray.h>
@@ -502,7 +503,7 @@ DecodeResult from_hex(VM& vm, StringView string, Optional<size_t> max_length)
         // d. Let byte be the integer value represented by hexits in base-16 notation, using the letters A-F and a-f
         //    for digits with values 10 through 15.
         // NOTE: We do this early so that we don't have to effectively parse hexits twice.
-        auto byte = AK::StringUtils::convert_to_uint_from_hex<u8>(hexits, AK::TrimWhitespace::No);
+        auto byte = AK::parse_hexadecimal_number<u8>(hexits, TrimWhitespace::No);
 
         // b. If hexits contains any code units which are not in "0123456789abcdefABCDEF", then
         if (!byte.has_value()) {

Libraries/LibJS/Runtime/Value.cpp

@@ -10,7 +10,6 @@
 #include <AK/Assertions.h>
 #include <AK/ByteString.h>
 #include <AK/CharacterTypes.h>
-#include <AK/FloatingPointStringConversions.h>
 #include <AK/StringBuilder.h>
 #include <AK/StringFloatingPointConversions.h>
 #include <AK/Utf8View.h>

Libraries/LibJS/Token.cpp

@@ -8,7 +8,6 @@
 #include "Token.h"
 #include <AK/Assertions.h>
 #include <AK/CharacterTypes.h>
-#include <AK/FloatingPointStringConversions.h>
 #include <AK/GenericLexer.h>
 #include <AK/StringBuilder.h>