Enable snapshots on MIPS. This is based on

src/x64/assembler-x64-inl.h

 // Copyright 2012 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 217 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() {
   if (IsCodedSpecially()) {
-    return Assembler::kCallTargetSize;
+    return Assembler::kSpecialTargetSize;
   } else {
-    return Assembler::kExternalTargetSize;
+    return kPointerSize;
   }
 }
 
 
 void RelocInfo::set_target_address(Address target, WriteBarrierMode mode) {
   ASSERT(IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY);
   if (IsCodeTarget(rmode_)) {
     Assembler::set_target_address_at(pc_, target);
     Object* target_code = Code::GetCodeFromTargetAddress(target);
     if (mode == UPDATE_WRITE_BARRIER && host() != NULL) {
@@ skipping 230 matching lines @@
   ASSERT(len_ == 1 || len_ == 2);
   int32_t* p = reinterpret_cast<int32_t*>(&buf_[len_]);
   *p = disp;
   len_ += sizeof(int32_t);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_ASSEMBLER_X64_INL_H_