Fix Debug::Break crash.

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4875 matching lines @@
     object_array->set(store_index, *value);
   }
   return *object;
 }
 
 
 // Check whether debugger and is about to step into the callback that is passed
 // to a built-in function such as Array.forEach.
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DebugCallbackSupportsStepping) {
 #ifdef ENABLE_DEBUGGER_SUPPORT
-  if (!isolate->IsDebuggerActive()) return isolate->heap()->false_value();
+  if (!isolate->IsDebuggerActive() || !isolate->debug()->StepInActive()) {
+    return isolate->heap()->false_value();
+  }
   CONVERT_ARG_CHECKED(Object, callback, 0);
   // We do not step into the callback if it's a builtin or not even a function.
   if (!callback->IsJSFunction() || JSFunction::cast(callback)->IsBuiltin()) {
     return isolate->heap()->false_value();
   }
   return isolate->heap()->true_value();
 #else
   return isolate->heap()->false_value();
 #endif  // ENABLE_DEBUGGER_SUPPORT
 }
@@ skipping 8809 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal