Remote DrainToImmutable() extension method

Since moving to System.Collections.Immutable 8.0, this extension method is no longer needed.

src/Shared/Microsoft.AspNetCore.Razor.Utilities.Shared/ImmutableArrayExtensions.cs

@@ -29,39 +29,6 @@ public static void SetCapacityIfLarger<T>(this ImmutableArray<T>.Builder builder
         }
     }
 
-    /// <summary>
-    ///  Returns the current contents as an <see cref="ImmutableArray{T}"/> and sets
-    ///  the collection to a zero length array.
-    /// </summary>
-    /// <remarks>
-    ///  If <see cref="ImmutableArray{T}.Builder.Capacity"/> equals
-    ///  <see cref="ImmutableArray{T}.Builder.Count"/>, the internal array will be extracted
-    ///  as an <see cref="ImmutableArray{T}"/> without copying the contents. Otherwise, the
-    ///  contents will be copied into a new array. The collection will then be set to a
-    ///  zero-length array.
-    /// </remarks>
-    /// <returns>An immutable array.</returns>
-    public static ImmutableArray<T> DrainToImmutable<T>(this ImmutableArray<T>.Builder builder)
-    {
-#if NET8_0_OR_GREATER
-        return builder.DrainToImmutable();
-#else
-        if (builder.Count == 0)
-        {
-            return [];
-        }
-
-        if (builder.Count == builder.Capacity)
-        {
-            return builder.MoveToImmutable();
-        }
-
-        var result = builder.ToImmutable();
-        builder.Clear();
-        return result;
-#endif
-    }
-
     public static ImmutableArray<TResult> SelectAsArray<T, TResult>(this ImmutableArray<T> source, Func<T, TResult> selector)
     {
         return source switch