Don't leak file names in Windows File::Stat().

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 450 matching lines @@
 }
 
 
 void File::Stat(const char* name, int64_t* data) {
   File::Type type = GetType(name, false);
   data[kType] = type;
   if (type != kDoesNotExist) {
     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) {
       data[kCreatedTime] = st.st_ctime;
       data[kModifiedTime] = st.st_mtime;
       data[kAccessedTime] = st.st_atime;
       data[kMode] = st.st_mode;
       data[kSize] = st.st_size;
     } else {
       data[kType] = File::kDoesNotExist;
     }
   }
@@ skipping 159 matching lines @@
     return kIdentical;
   } else {
     return kDifferent;
   }
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)