Fix warnings on Win64.

src/x64/assembler-x64-inl.h

 // Copyright 2009 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 158 matching lines @@
   if (op.rex_ != 0) emit(0x40 | op.rex_);
 }
 
 
 Address Assembler::target_address_at(Address pc) {
   return Memory::int32_at(pc) + pc + 4;
 }
 
 
 void Assembler::set_target_address_at(Address pc, Address target) {
-  Memory::int32_at(pc) = target - pc - 4;
+  Memory::int32_at(pc) = static_cast<int32_t>(target - pc - 4);
   CPU::FlushICache(pc, sizeof(int32_t));
 }
 
 Handle<Object> Assembler::code_target_object_handle_at(Address pc) {
   return code_targets_[Memory::int32_at(pc)];
 }
 
 // -----------------------------------------------------------------------------
 // Implementation of RelocInfo
 
 // The modes possibly affected by apply must be in kApplyMask.
 void RelocInfo::apply(intptr_t delta) {
   if (IsInternalReference(rmode_)) {
     // absolute code pointer inside code object moves with the code object.
-    Memory::Address_at(pc_) += delta;
+    Memory::Address_at(pc_) += static_cast<int32_t>(delta);
   } else if (IsCodeTarget(rmode_)) {
-    Memory::int32_at(pc_) -= delta;
+    Memory::int32_at(pc_) -= static_cast<int32_t>(delta);
   } else if (rmode_ == JS_RETURN && IsPatchedReturnSequence()) {
     // Special handling of js_return when a break point is set (call
     // instruction has been inserted).
-    Memory::int32_at(pc_ + 1) -= delta;  // relocate entry
+    Memory::int32_at(pc_ + 1) -= static_cast<int32_t>(delta);  // relocate entry
   }
 }
 
 
 Address RelocInfo::target_address() {
   ASSERT(IsCodeTarget(rmode_) || rmode_ == RUNTIME_ENTRY);
   if (IsCodeTarget(rmode_)) {
     return Assembler::target_address_at(pc_);
   } else {
     return Memory::Address_at(pc_);
@@ skipping 132 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_