Remove unused functions (#79234)

Author: CyrusNajmabadi

src/Compilers/Core/Portable/InternalUtilities/Hash.cs

@@ -302,18 +302,6 @@ internal static int GetCaseInsensitiveFNVHashCode(ReadOnlySpan<char> data)
             return hashCode;
         }
 
-        /// <summary>
-        /// Compute the hashcode of a sub-string using FNV-1a
-        /// See http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
-        /// </summary>
-        /// <param name="text">The input string</param>
-        /// <param name="start">The start index of the first character to hash</param>
-        /// <returns>The FNV-1a hash code of the substring beginning at <paramref name="start"/> and ending at the end of the string.</returns>
-        internal static int GetFNVHashCode(string text, int start)
-        {
-            return GetFNVHashCode(text, start, length: text.Length - start);
-        }
-
         /// <summary>
         /// Compute the hashcode of a string using FNV-1a
         /// See http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function

src/Compilers/Core/Portable/InternalUtilities/StringTable.cs

@@ -561,19 +561,6 @@ private void AddSharedEntry(int hashCode, string text)
             Volatile.Write(ref arr[idx].Text, text);
         }
 
-        internal static string AddShared(StringBuilder chars)
-        {
-            var hashCode = Hash.GetFNVHashCode(chars);
-
-            string? shared = FindSharedEntry(chars, hashCode);
-            if (shared != null)
-            {
-                return shared;
-            }
-
-            return AddSharedSlow(hashCode, chars);
-        }
-
         private static string AddSharedSlow(int hashCode, StringBuilder builder)
         {
             string text = builder.ToString();