Remove virtual modifier from GetDatePart

src/libraries/System.Private.CoreLib/src/System/Globalization/HebrewCalendar.cs

@@ -432,7 +432,7 @@ internal static int GetLunarMonthDay(int gregorianYear, DateBuffer lunarDate)
         /// Returns a given date part of this DateTime. This method is used
         /// to compute the year, day-of-year, month, or day part.
         /// </summary>
-        internal virtual int GetDatePart(long ticks, int part)
+        private static int GetDatePart(long ticks, int part)
         {
             // The Gregorian year, month, day value for ticks.
             int hebrewYearType;                // lunar year type

src/libraries/System.Private.CoreLib/src/System/Globalization/HijriCalendar.cs

@@ -192,7 +192,7 @@ internal static void CheckYearMonthRange(int year, int month, int era)
         /// In order to get the exact Hijri year, we compare the exact absolute date for HijriYear and (HijriYear + 1).
         /// From here, we can get the correct Hijri year.
         /// </summary>
-        internal virtual int GetDatePart(long ticks, int part)
+        private int GetDatePart(long ticks, int part)
         {
             CheckTicksRange(ticks);
 

src/libraries/System.Private.CoreLib/src/System/Globalization/JulianCalendar.cs

@@ -111,7 +111,7 @@ internal static void CheckDayRange(int year, int month, int day)
         /// Returns a given date part of this DateTime. This method is used
         /// to compute the year, day-of-year, month, or day part.
         /// </summary>
-        internal static int GetDatePart(long ticks, int part)
+        private static int GetDatePart(long ticks, int part)
         {
             // Gregorian 1/1/0001 is Julian 1/3/0001. Remember DateTime(0) is referred to Gregorian 1/1/0001.
             // The following line convert Gregorian ticks to Julian ticks.

src/libraries/System.Private.CoreLib/src/System/Globalization/PersianCalendar.cs

@@ -141,7 +141,7 @@ private static int DaysInPreviousMonths(int month)
             return DaysToMonth[month];
         }
 
-        internal int GetDatePart(long ticks, int part)
+        private int GetDatePart(long ticks, int part)
         {
             CheckTicksRange(ticks);