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

runtime/vm/instructions_dbc.cc

Index: runtime/vm/instructions_dbc.cc
diff --git a/runtime/vm/instructions_dbc.cc b/runtime/vm/instructions_dbc.cc
index 7667a5f2b6b56f2bc0e92ca08f05303c21be9cc8..3559fbfeb9caa6db7cffe129480b90124178744d 100644
--- a/runtime/vm/instructions_dbc.cc
+++ b/runtime/vm/instructions_dbc.cc
@@ -168,14 +168,6 @@ void CallPattern::SetTargetCode(const Code& target_code) const {
 }
 
 
-void CallPattern::InsertDeoptCallAt(uword pc) {
-  const uint8_t argc = Bytecode::IsCallOpcode(Bytecode::At(pc))
-                           ? Bytecode::DecodeArgc(Bytecode::At(pc))
-                           : 0;
-  *reinterpret_cast<Instr*>(pc) = Bytecode::Encode(Bytecode::kDeopt, argc, 0);
-}
-
-
 SwitchableCallPattern::SwitchableCallPattern(uword pc, const Code& code)
     : object_pool_(ObjectPool::Handle(code.GetObjectPool())),
       data_pool_index_(-1),