LibJS: Add "Month dd, yy hh:mm:ss" Date format

Required by Discord's Birthday page.

Userland/Libraries/LibJS/Runtime/DateConstructor.cpp

@@ -147,12 +147,13 @@ static double parse_simplified_iso8601(DeprecatedString const& iso_8601)
     return time_clip(time_ms);
 }
 
-static constexpr AK::Array<StringView, 5> extra_formats = {
+static constexpr AK::Array<StringView, 6> extra_formats = {
     "%a %b %e %T %z %Y"sv,
     "%m/%e/%Y"sv,
     "%m/%e/%Y %R %z"sv,
     "%Y/%m/%e %R"sv,
     "%Y-%m-%e %R"sv,
+    "%B %e, %Y %T"sv,
 };
 
 static double parse_date_string(DeprecatedString const& date_string)
@@ -166,6 +167,7 @@ static double parse_date_string(DeprecatedString const& date_string)
     // And: "4/17/2019"
     // And: "12/05/2022 10:00 -0800"
     // And: "2014/11/14 13:05" or "2014-11-14 13:05"
+    // And: "June 5, 2023 17:00:00"
     // FIXME: Exactly what timezone and which additional formats we should support is unclear.
     //        Both Chrome and Firefox seem to support "4/17/2019 11:08 PM +0000" with most parts
     //        being optional, however this is not clearly documented anywhere.

Userland/Libraries/LibJS/Tests/builtins/Date/Date.parse.js

@@ -100,3 +100,22 @@ test("yy{/,-}mm{/,-}dd hh:mm extension", () => {
     expectStringToGiveDate("2014/11/14 13:05", 2014, 11, 14, 13, 5);
     expectStringToGiveDate("2014-11-14 13:05", 2014, 11, 14, 13, 5);
 });
+
+test("Month dd, yy hh:mm:ss extension", () => {
+    function expectStringToGiveDate(input, fullYear, month, dayInMonth, hours, minutes, seconds) {
+        // Since the timezone is not specified we just say it has to equal the date parts.
+        const date = new Date(Date.parse(input));
+        expect(date.getFullYear()).toBe(fullYear);
+        expect(date.getMonth() + 1).toBe(month);
+        expect(date.getDate()).toBe(dayInMonth);
+        expect(date.getHours()).toBe(hours);
+        expect(date.getMinutes()).toBe(minutes);
+        expect(date.getSeconds()).toBe(seconds);
+    }
+
+    // Examples from Discord's Birthday JavaScript for May 2023.
+    expectStringToGiveDate("May 15, 2023 17:00:00", 2023, 5, 15, 17, 0, 0);
+    expectStringToGiveDate("May 22, 2023 17:00:00", 2023, 5, 22, 17, 0, 0);
+    expectStringToGiveDate("May 30, 2023 17:00:00", 2023, 5, 30, 17, 0, 0);
+    expectStringToGiveDate("June 5, 2023 17:00:00", 2023, 6, 5, 17, 0, 0);
+});