[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..43e12e99b724359fe9164c639da8e982dc84223f 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -896,7 +896,11 @@ 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)) {
+    if (!Compiler::Compile(function, Compiler::KEEP_EXCEPTION)) return;
+    Deoptimizer::DeoptimizeFunction(*function);
+    return;
+  }
   if (*function == thread_local_.ignore_step_into_function_) return;
   thread_local_.ignore_step_into_function_ = Smi::kZero;
   FloodWithOneShot(Handle<SharedFunctionInfo>(function->shared(), isolate_));