SignalInfo must store fd_ as an intptr_t not an int.

runtime/bin/process.h

 // 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.
 
 #ifndef BIN_PROCESS_H_
 #define BIN_PROCESS_H_
 
 #include "bin/builtin.h"
 #include "bin/io_buffer.h"
 #include "bin/lockers.h"
@@ skipping 130 matching lines @@
   static int global_exit_code_;
   static Mutex* global_exit_code_mutex_;
 
   DISALLOW_ALLOCATION();
   DISALLOW_IMPLICIT_CONSTRUCTORS(Process);
 };
 
 
 class SignalInfo {
  public:
-  SignalInfo(int fd, int signal, SignalInfo* next)
+  SignalInfo(intptr_t fd, intptr_t signal, SignalInfo* next)
       : fd_(fd),
         signal_(signal),
         // SignalInfo is expected to be created when in a isolate.
         port_(Dart_GetMainPortId()),
         next_(next),
         prev_(NULL) {
     if (next_ != NULL) {
       next_->prev_ = this;
     }
   }
 
   ~SignalInfo();
 
   void Unlink() {
     if (prev_ != NULL) {
       prev_->next_ = next_;
     }
     if (next_ != NULL) {
       next_->prev_ = prev_;
     }
   }
 
-  int fd() const { return fd_; }
-  int signal() const { return signal_; }
+  intptr_t fd() const { return fd_; }
+  intptr_t signal() const { return signal_; }
   Dart_Port port() const { return port_; }
   SignalInfo* next() const { return next_; }
 
  private:
-  int fd_;
-  int signal_;
+  intptr_t fd_;
+  intptr_t signal_;
   // The port_ is used to identify what isolate the signal-info belongs to.
   Dart_Port port_;
   SignalInfo* next_;
   SignalInfo* prev_;
 };
 
 
 // Utility class for collecting the output when running a process
 // synchronously by using Process::Wait. This class is sub-classed in
 // the platform specific files to implement reading into the buffers
@@ skipping 92 matching lines @@
   intptr_t data_size_;
 
   // Number of free bytes in the last node in the list.
   intptr_t free_size_;
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_PROCESS_H_