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

runtime/vm/deopt_instructions.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.
 
 #include "vm/deopt_instructions.h"
 
 #include "vm/assembler.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/intermediate_language.h"
@@ skipping 405 matching lines @@
     *dest_addr = Smi::RawValue(0);
     deopt_context->DeferRetAddrMaterialization(
         object_table_index_, deopt_id_, dest_addr);
   }
 
   intptr_t object_table_index() const { return object_table_index_; }
   intptr_t deopt_id() const { return deopt_id_; }
 
  private:
   static const intptr_t kFieldWidth = kBitsPerWord / 2;
-  class ObjectTableIndex : public BitField<intptr_t, 0, kFieldWidth> { };
-  class DeoptId : public BitField<intptr_t, kFieldWidth, kFieldWidth> { };
+  class ObjectTableIndex :
+      public BitField<intptr_t, intptr_t, 0, kFieldWidth> { };
+  class DeoptId :
+      public BitField<intptr_t, intptr_t, kFieldWidth, kFieldWidth> { };
 
   const intptr_t object_table_index_;
   const intptr_t deopt_id_;
 
   DISALLOW_COPY_AND_ASSIGN(DeoptRetAddressInstr);
 };
 
 
 // Deoptimization instruction moving a constant stored at 'object_table_index'.
 class DeoptConstantInstr : public DeoptInstr {
@@ skipping 102 matching lines @@
         hi_.ToCString());
   }
 
   virtual int64_t GetValue(DeoptContext* deopt_context) {
     return Utils::LowHighTo64Bits(
         lo_.Value<uint32_t>(deopt_context), hi_.Value<int32_t>(deopt_context));
   }
 
  private:
   static const intptr_t kFieldWidth = kBitsPerWord / 2;
-  class LoRegister : public BitField<intptr_t, 0, kFieldWidth> { };
-  class HiRegister : public BitField<intptr_t, kFieldWidth, kFieldWidth> { };
+  class LoRegister : public BitField<intptr_t, intptr_t, 0, kFieldWidth> { };
+  class HiRegister :
+      public BitField<intptr_t, intptr_t, kFieldWidth, kFieldWidth> { };
 
   const CpuRegisterSource lo_;
   const CpuRegisterSource hi_;
 
   DISALLOW_COPY_AND_ASSIGN(DeoptMintPairInstr);
 };
 
 
 template<DeoptInstr::Kind K, typename T>
 class DeoptIntInstr : public DeoptIntegerInstrBase {
@@ skipping 742 matching lines @@
                           Smi* offset,
                           TypedData* info,
                           Smi* reason) {
   intptr_t i = index * kEntrySize;
   *offset ^= table.At(i);
   *info ^= table.At(i + 1);
   *reason ^= table.At(i + 2);
 }
 
 }  // namespace dart