Change modified method instead of adding overloads

The unarchiveTopLevelObjectWithData which returns Any? (instead of
AnyObject?) was added in Swift 4 and has only shipped in the betas so
far. Instead of adding new overloads which take different types, we
should just fix this one and call it a day.

Author: Itai Ferber

stdlib/public/SDK/Foundation/NSCoder.swift

@@ -144,29 +144,15 @@ extension NSKeyedUnarchiver {
     return result as AnyObject?
   }
 
-  @nonobjc
-  @available(swift, obsoleted: 4)
-  @available(OSX 10.11, iOS 9.0, *)
-  public class func unarchiveTopLevelObjectWithData(_ data: Data) throws -> AnyObject? {
-      return try self.unarchiveTopLevelObjectWithData(data as NSData)
-  }
-
   @nonobjc
   @available(swift, introduced: 4)
   @available(OSX 10.11, iOS 9.0, *)
-  public class func unarchiveTopLevelObjectWithData(_ data: NSData) throws -> Any? {
+  public class func unarchiveTopLevelObjectWithData(_ data: Data) throws -> Any? {
     var error: NSError?
-    let result = __NSKeyedUnarchiverUnarchiveObject(self, data, &error)
+    let result = __NSKeyedUnarchiverUnarchiveObject(self, data as NSData, &error)
     try resolveError(error)
     return result
   }
-
-  @nonobjc
-  @available(swift, introduced: 4)
-  @available(OSX 10.11, iOS 9.0, *)
-  public class func unarchiveTopLevelObjectWithData(_ data: Data) throws -> Any? {
-      return try self.unarchiveTopLevelObjectWithData(data as NSData)
-  }
 }