Enable snapshots on MIPS. This is based on

src/ia32/assembler-ia32-inl.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 70 matching lines @@
 
 Address RelocInfo::target_address_address() {
   ASSERT(IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY
                               || rmode_ == EMBEDDED_OBJECT
                               || rmode_ == EXTERNAL_REFERENCE);
   return reinterpret_cast<Address>(pc_);
 }
 
 
 int RelocInfo::target_address_size() {
-  return Assembler::kExternalTargetSize;
+  return Assembler::kSpecialTargetSize;
 }
 
 
 void RelocInfo::set_target_address(Address target, WriteBarrierMode mode) {
   Assembler::set_target_address_at(pc_, target);
   ASSERT(IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY);
   if (mode == UPDATE_WRITE_BARRIER && host() != NULL && IsCodeTarget(rmode_)) {
     Object* target_code = Code::GetCodeFromTargetAddress(target);
     host()->GetHeap()->incremental_marking()->RecordWriteIntoCode(
         host(), this, HeapObject::cast(target_code));
@@ skipping 362 matching lines @@
 
 Operand::Operand(int32_t disp, RelocInfo::Mode rmode) {
   // [disp/r]
   set_modrm(0, ebp);
   set_dispr(disp, rmode);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_ASSEMBLER_IA32_INL_H_