Remove a brittle assertion from Turbofan lazy deoptimization handling.

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties-inl.h"
@@ skipping 964 matching lines @@
     // No other combinations are possible.
     UNREACHABLE();
   }
 }
 
 
 void CodeGenerator::AddNopForSmiCodeInlining() { __ nop(); }
 
 #undef __
 
-#ifdef DEBUG
-
-// Checks whether the code between start_pc and end_pc is a no-op.
-bool CodeGenerator::IsNopForSmiCodeInlining(Handle<Code> code, int start_pc,
-                                            int end_pc) {
-  if (start_pc + 1 != end_pc) {
-    return false;
-  }
-  return *(code->instruction_start() + start_pc) ==
-         v8::internal::Assembler::kNopByte;
-}
-
-#endif
-
 }  // namespace internal
 }  // namespace compiler
 }  // namespace v8