Expose function CheckDebugBreak in the debugger api

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index aaf6865bc8e6044b551f4e3bf81751494b3159e7..c287062126d3e903e55002d0cf1c2dc2898a448b 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6907,6 +6907,12 @@ void Debug::CancelDebugBreak(Isolate* isolate) {
 }
 
 
+bool Debug::CheckDebugBreak(Isolate* isolate) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+  return internal_isolate->stack_guard()->CheckDebugBreak();
+}
+
+
 void Debug::DebugBreakForCommand(Isolate* isolate, ClientData* data) {
   i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
   internal_isolate->debug()->EnqueueDebugCommand(data);