Reapply "Lazy deopt without code patching."

runtime/vm/instructions_arm64.h

Index: runtime/vm/instructions_arm64.h
diff --git a/runtime/vm/instructions_arm64.h b/runtime/vm/instructions_arm64.h
index 80de324e656b74bb65fa546c312203beddf11166..e3c1d4d0f3bda027b4ff481e9ab8450eea626580 100644
--- a/runtime/vm/instructions_arm64.h
+++ b/runtime/vm/instructions_arm64.h
@@ -64,14 +64,6 @@ class CallPattern : public ValueObject {
   RawCode* TargetCode() const;
   void SetTargetCode(const Code& target) const;
 
-  // This constant length is only valid for inserted call patterns used for
-  // lazy deoptimization. Regular call pattern may vary in length.
-  static const int kDeoptCallLengthInInstructions = 5;
-  static const int kDeoptCallLengthInBytes =
-      kDeoptCallLengthInInstructions * Instr::kInstrSize;
-
-  static void InsertDeoptCallAt(uword pc, uword target_address);
-
  private:
   const ObjectPool& object_pool_;