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

runtime/bin/file.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 "bin/file.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
@@ skipping 74 matching lines @@
   const char* filename =
       DartUtils::GetStringValue(Dart_GetNativeArgument(args, 0));
   int64_t mode = DartUtils::GetIntegerValue(Dart_GetNativeArgument(args, 1));
   File::DartFileOpenMode dart_file_mode =
       static_cast<File::DartFileOpenMode>(mode);
   File::FileOpenMode file_mode = File::DartModeToFileMode(dart_file_mode);
   // Check that the file exists before opening it only for
   // reading. This is to prevent the opening of directories as
   // files. Directories can be opened for reading using the posix
   // 'open' call.
-  File* file = File::ScopedOpen(filename, file_mode);
+  File* file = File::Open(filename, file_mode);
   if (file != NULL) {
     Dart_SetReturnValue(args,
                         Dart_NewInteger(reinterpret_cast<intptr_t>(file)));
   } else {
     Dart_SetReturnValue(args, DartUtils::NewDartOSError());
   }
 }
 
 
 void FUNCTION_NAME(File_Exists)(Dart_NativeArguments args) {
@@ skipping 564 matching lines @@
 CObject* File::OpenRequest(const CObjectArray& request) {
   File* file = NULL;
   if ((request.Length() == 2) &&
       request[0]->IsString() &&
       request[1]->IsInt32()) {
     CObjectString filename(request[0]);
     CObjectInt32 mode(request[1]);
     File::DartFileOpenMode dart_file_mode =
         static_cast<File::DartFileOpenMode>(mode.Value());
     File::FileOpenMode file_mode = File::DartModeToFileMode(dart_file_mode);
-    file = File::ScopedOpen(filename.CString(), file_mode);
+    file = File::Open(filename.CString(), file_mode);
     if (file != NULL) {
       return new CObjectIntptr(
           CObject::NewIntptr(reinterpret_cast<intptr_t>(file)));
     } else {
       return CObject::NewOSError();
     }
   }
   return CObject::IllegalArgumentError();
 }
 
@@ skipping 539 matching lines @@
       return CObject::IllegalArgumentError();
     }
   }
   return CObject::IllegalArgumentError();
 }
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // !defined(DART_IO_DISABLED)