Use off-heap data for class check instructions

runtime/vm/assembler_arm64.cc

 // Copyright (c) 2014, 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/globals.h"  // NOLINT
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/cpu.h"
 #include "vm/longjump.h"
@@ skipping 602 matching lines @@
                                           const Object& equivalence) {
   const Code& target = Code::ZoneHandle(stub_entry.code());
   const int32_t offset = ObjectPool::element_offset(
       object_pool_wrapper_.FindObject(target, equivalence));
   LoadWordFromPoolOffset(CODE_REG, offset);
   ldr(TMP, FieldAddress(CODE_REG, Code::entry_point_offset()));
   blr(TMP);
 }
 
 
+void Assembler::AddImmediate(Register dest, int64_t imm) {
+  AddImmediate(dest, dest, imm);
+}
+
+
 void Assembler::AddImmediate(Register dest, Register rn, int64_t imm) {
   Operand op;
   if (imm == 0) {
     if (dest != rn) {
       mov(dest, rn);
     }
     return;
   }
   if (Operand::CanHold(imm, kXRegSizeInBits, &op) == Operand::Immediate) {
     add(dest, rn, op);
@@ skipping 938 matching lines @@
   str(tmp, Address(addr, 7), kUnsignedByte);
   if (sz == kDoubleWord) {
     return;
   }
   UNIMPLEMENTED();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64