Add File.copy(Sync) to dart:io.

runtime/bin/file_win.cc

 // Copyright (c) 2012, 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_WINDOWS)
 
 #include "bin/file.h"
 
 #include <fcntl.h>  // NOLINT
@@ skipping 304 matching lines @@
     free(const_cast<wchar_t*>(system_old_path));
     free(const_cast<wchar_t*>(system_new_path));
     return (move_status != 0);
   } else {
     SetLastError(ERROR_FILE_NOT_FOUND);
   }
   return false;
 }
 
 
+bool File::Copy(const char* old_path, const char* new_path) {
+  File::Type type = GetType(old_path, false);
+  if (type == kIsFile) {
+    const wchar_t* system_old_path = StringUtils::Utf8ToWide(old_path);
+    const wchar_t* system_new_path = StringUtils::Utf8ToWide(new_path);
+    bool success = CopyFileExW(system_old_path,
+                               system_new_path,
+                               NULL,
+                               NULL,
+                               NULL,
+                               0) != 0;
+    free(const_cast<wchar_t*>(system_old_path));
+    free(const_cast<wchar_t*>(system_new_path));
+    return success;
+  } else {
+    SetLastError(ERROR_FILE_NOT_FOUND);
+  }
+  return false;
+}
+
+
 off64_t File::LengthFromPath(const char* name) {
   struct __stat64 st;
   const wchar_t* system_name = StringUtils::Utf8ToWide(name);
   int stat_status = _wstat64(system_name, &st);
   free(const_cast<wchar_t*>(system_name));
   if (stat_status == 0) {
     return st.st_size;
   }
   return -1;
 }
@@ skipping 271 matching lines @@
     return kIdentical;
   } else {
     return kDifferent;
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)