Do not enter the debugger when debugger is not active.

src/execution.cc

Index: src/execution.cc
diff --git a/src/execution.cc b/src/execution.cc
index 40ed7de4140d1ea5716c5bc625bd46c00d26fa9b..2613c20f0f4ed1b23e47e211fa8839ca7a22af58 100644
--- a/src/execution.cc
+++ b/src/execution.cc
@@ -832,6 +832,11 @@ Object* Execution::DebugBreakHelper() {
     return isolate->heap()->undefined_value();
   }
 
+  // Ignore debug break if debugger is not active.
+  if (!isolate->debugger()->IsDebuggerActive()) {
+    return isolate->heap()->undefined_value();
+  }
+
   StackLimitCheck check(isolate);
   if (check.HasOverflowed()) {
     return isolate->heap()->undefined_value();