Do not rely on code patching on DBC for lazy deoptimization.

runtime/vm/code_patcher_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"  // Needed here to get TARGET_ARCH_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/code_patcher.h"
 #include "vm/cpu.h"
 #include "vm/instructions.h"
@@ skipping 49 matching lines @@
 
 void CodePatcher::PatchPoolPointerCallAt(uword return_address,
                                          const Code& code,
                                          const Code& new_target) {
   ASSERT(code.ContainsInstructionAt(return_address));
   PoolPointerCall call(return_address, code);
   call.SetTarget(new_target);
 }
 
 
-void CodePatcher::InsertDeoptimizationCallAt(uword start) {
-  UNREACHABLE();
-}
-
-
 RawCode* CodePatcher::GetInstanceCallAt(uword return_address,
                                         const Code& code,
                                         ICData* ic_data) {
   ASSERT(code.ContainsInstructionAt(return_address));
   CallPattern call(return_address, code);
   if (ic_data != NULL) {
     *ic_data = call.IcData();
   }
   return call.TargetCode();
 }
@@ skipping 63 matching lines @@
                                       NativeFunction* target) {
   ASSERT(code.ContainsInstructionAt(return_address));
   NativeCallPattern call(return_address, code);
   *target = call.native_function();
   return call.target();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64