Fuchsia: Adds File::Copy()

runtime/bin/directory_fuchsia.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_FUCHSIA)
 
 #include "bin/directory.h"
 
 #include <dirent.h>    // NOLINT
@@ skipping 337 matching lines @@
 
 
 bool Directory::Delete(const char* dir_name, bool recursive) {
   if (!recursive) {
     if ((File::GetType(dir_name, false) == File::kIsLink) &&
         (File::GetType(dir_name, true) == File::kIsDirectory)) {
       return NO_RETRY_EXPECTED(unlink(dir_name)) == 0;
     }
     return NO_RETRY_EXPECTED(rmdir(dir_name)) == 0;
   } else {
+    // TODO(MG-416): After the issue is addressed, this can use the same code
+    // as on Linux, etc.
     UNIMPLEMENTED();
     return false;
   }
 }
 
 
 bool Directory::Rename(const char* path, const char* new_path) {
   ExistsResult exists = Exists(path);
   if (exists != EXISTS) {
     return false;
   }
   return (NO_RETRY_EXPECTED(rename(path, new_path)) == 0);
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_FUCHSIA)