Fix some more shorten-64-to-32 warnings:

runtime/vm/deopt_instructions.h

 // 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.
 
 #ifndef VM_DEOPT_INSTRUCTIONS_H_
 #define VM_DEOPT_INSTRUCTIONS_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
@@ skipping 381 matching lines @@
   const char* ToCString() const {
     if (is_register()) {
       return Name(reg());
     } else {
       return Thread::Current()->zone()->PrintToString(
           "s%" Pd "", raw_index());
     }
   }
 
  private:
-  class KindField : public BitField<intptr_t, 0, 1> { };
-  class RawIndexField : public BitField<intptr_t, 1, kBitsPerWord - 1> { };
+  class KindField : public BitField<intptr_t, intptr_t, 0, 1> { };
+  class RawIndexField :
+      public BitField<intptr_t, intptr_t, 1, kBitsPerWord - 1> { };
 
   bool is_register() const {
     return KindField::decode(source_index_) == kRegister;
   }
   intptr_t raw_index() const { return RawIndexField::decode(source_index_); }
 
   RegisterType reg() const { return static_cast<RegisterType>(raw_index()); }
 
   static const char* Name(Register reg) {
     return Assembler::RegisterName(reg);
@@ skipping 122 matching lines @@
                        Smi* offset,
                        TypedData* info,
                        Smi* reason_and_flags);
 
   static RawSmi* EncodeReasonAndFlags(ICData::DeoptReasonId reason,
                                       uint32_t flags) {
     return Smi::New(ReasonField::encode(reason) |
                     FlagsField::encode(flags));
   }
 
-  class ReasonField : public BitField<ICData::DeoptReasonId, 0, 8> { };
-  class FlagsField : public BitField<uint32_t, 8, 8> { };
+  class ReasonField :
+      public BitField<intptr_t, ICData::DeoptReasonId, 0, 8> { };
+  class FlagsField : public BitField<intptr_t, uint32_t, 8, 8> { };
 
  private:
   static const intptr_t kEntrySize = 3;
 };
 
 }  // namespace dart
 
 #endif  // VM_DEOPT_INSTRUCTIONS_H_