[inspector] deoptimize function in Debug::PrepareStepIn

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index 73af4cf7f71b390b7f0b46462417479273cb8dae..b6b37fc8f1c7485ca9a44a327af56d0f2bf93f5c 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -896,7 +896,10 @@ void Debug::PrepareStepIn(Handle<JSFunction> function) {
   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_));