[inspector] ignores debugger; in blackboxed code

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index a21bfde25c1c5fab931337dc0679f97ddf16e9a9..418b8eb2481d84020a22a43658aabed70412edd3 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -2139,8 +2139,7 @@ void Debug::HandleDebugBreak() {
     if (fun && fun->IsJSFunction()) {
       // Don't stop in builtin functions.
       if (!JSFunction::cast(fun)->shared()->IsSubjectToDebugging()) return;
-      if (isolate_->stack_guard()->CheckDebugBreak() &&
-          IsBlackboxed(JSFunction::cast(fun)->shared())) {
+      if (IsBlackboxed(JSFunction::cast(fun)->shared())) {

[Yang, 2017/01/25 06:03:52]

Why do we need to deoptimize the function? We don't do this for regular
optimized functions that have a debugger statement. Simply returning should be
fine imo.

[kozy, 2017/01/25 06:10:44]

I think when we schedule pause on next statement for async break points, we can
enter to this function on function call and we would like to deoptimize this
function if it's blackboxed to correctly break on enter to inner function.
As proof: one of inspector test about async breakpoints are flaky without this
code.

[Yang, 2017/01/25 08:32:34]

As discussed, please also deopt the function for the case of not subject to
debugging. And add a comment for why this is necessary, with a TODO to remove
once we have break-on-entry.

         Deoptimizer::DeoptimizeFunction(JSFunction::cast(fun));
         return;
       }