[futex] Allow debugger to break in the middle of a futexWait

src/debug/debug.cc

Index: src/debug/debug.cc
diff --git a/src/debug/debug.cc b/src/debug/debug.cc
index 5dc1742137b5942daf64f3eeca772bf97c59cdf9..f6969b12389eb906d8eae0121469041b505ad0d2 100644
--- a/src/debug/debug.cc
+++ b/src/debug/debug.cc
@@ -41,6 +41,7 @@ Debug::Debug(Isolate* isolate)
       in_debug_event_listener_(false),
       break_on_exception_(false),
       break_on_uncaught_exception_(false),
+      break_in_nondebuggable_(false),
       debug_info_list_(NULL),
       isolate_(isolate) {
   ThreadInit();
@@ -2244,7 +2245,10 @@ void Debug::HandleDebugBreak() {
     Object* fun = it.frame()->function();
     if (fun && fun->IsJSFunction()) {
       // Don't stop in builtin functions.
-      if (!JSFunction::cast(fun)->IsSubjectToDebugging()) return;
+      if (!(JSFunction::cast(fun)->IsSubjectToDebugging() ||
+            break_in_nondebuggable_)) {
+        return;
+      }
       GlobalObject* global = JSFunction::cast(fun)->context()->global_object();
       // Don't stop in debugger functions.
       if (IsDebugGlobal(global)) return;