[windows] Make most file_win.cc functions use malloc for string conversions.

runtime/bin/socket_win.cc

 // Copyright (c) 2013, 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.
 
 #if !defined(DART_IO_DISABLED)
 
 #include "platform/globals.h"
 #if defined(TARGET_OS_WINDOWS)
 
 #include "bin/socket.h"
@@ skipping 352 matching lines @@
     SetLastError(error_code);
     *os_error = new OSError();
     return false;
   }
   return true;
 }
 
 
 bool Socket::ParseAddress(int type, const char* address, RawAddr* addr) {
   int result;
-  const wchar_t* system_address = StringUtilsWin::Utf8ToWide(address);
+  Utf8ToWideScope system_address(address);
   if (type == SocketAddress::TYPE_IPV4) {
-    result = InetPton(AF_INET, system_address, &addr->in.sin_addr);
+    result = InetPton(AF_INET, system_address.wide(), &addr->in.sin_addr);
   } else {
     ASSERT(type == SocketAddress::TYPE_IPV6);
-    result = InetPton(AF_INET6, system_address, &addr->in6.sin6_addr);
+    result = InetPton(AF_INET6, system_address.wide(), &addr->in6.sin6_addr);
   }
   return result == 1;
 }
 
 
 intptr_t Socket::CreateBindDatagram(const RawAddr& addr, bool reuseAddress) {
   SOCKET s = socket(addr.ss.ss_family, SOCK_DGRAM, IPPROTO_UDP);
   if (s == INVALID_SOCKET) {
     return -1;
   }
@@ skipping 331 matching lines @@
                     reinterpret_cast<char *>(&mreq),
                     sizeof(mreq)) == 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // defined(TARGET_OS_WINDOWS)
 
 #endif  // !defined(DART_IO_DISABLED)