[inspector] deoptimize function in Debug::PrepareStepIn

src/debug/debug.cc

 // Copyright 2012 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/debug/debug.h"
 
 #include <memory>
 
 #include "src/api.h"
 #include "src/arguments.h"
@@ skipping 878 matching lines @@
   break_points_hit->Shrink(break_points_hit_count);
   return break_points_hit;
 }
 
 void Debug::PrepareStepIn(Handle<JSFunction> function) {
   CHECK(last_step_action() >= StepIn);
   if (ignore_events()) return;
   if (in_debug_scope()) return;
   if (break_disabled()) return;
   Handle<SharedFunctionInfo> shared(function->shared());
-  if (IsBlackboxed(shared)) return;
+  if (IsBlackboxed(shared)) {
+    EnsureDebugInfo(shared);

[Yang, 2017/03/31 07:20:42]

We don't want a DebugInfo, since we are not going to set break points in here.

What you want is
  Deoptimizer::DeoptimizeFunction(frame->function());

See Debug::PrepareStepOnThrow for example.

+    return;
+  }
   if (*function == thread_local_.ignore_step_into_function_) return;
   thread_local_.ignore_step_into_function_ = Smi::kZero;
   FloodWithOneShot(Handle<SharedFunctionInfo>(function->shared(), isolate_));
 }
 
 void Debug::PrepareStepInSuspendedGenerator() {
   CHECK(has_suspended_generator());
   if (ignore_events()) return;
   if (in_debug_scope()) return;
   if (break_disabled()) return;
@@ skipping 1585 matching lines @@
     isolate_->Throw(*isolate_->factory()->NewEvalError(
         MessageTemplate::kNoSideEffectDebugEvaluate));
   }
   isolate_->set_needs_side_effect_check(old_needs_side_effect_check_);
   isolate_->debug()->UpdateHookOnFunctionCall();
   isolate_->debug()->side_effect_check_failed_ = false;
 }
 
 }  // namespace internal
 }  // namespace v8