Provide a counter for thrown JavaScript errors per context

src/contexts.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/contexts.h"
 
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
 #include "src/scopeinfo.h"
@@ skipping 571 matching lines @@
 
 bool Context::IsBootstrappingOrGlobalObject(Isolate* isolate, Object* object) {
   // During bootstrapping we allow all objects to pass as global
   // objects. This is necessary to fix circular dependencies.
   return isolate->heap()->gc_state() != Heap::NOT_IN_GC ||
       isolate->bootstrapper()->IsActive() ||
       object->IsGlobalObject();
 }
 #endif
 
+
+void Context::IncrementErrorsThrown() {
+  DCHECK(IsNativeContext());
+
+  int previous_value = Smi::cast(errors_thrown())->value();

[Yang, 2015/11/02 05:48:57]

this cast would be unnecessary if the type of this field is defined as Smi.

[Michael Hablich, 2015/11/04 10:58:07]

Done.

+  set_errors_thrown(Smi::FromInt(previous_value+1));
+}
+
+
+int Context::GetErrorsThrown() {
+  return Smi::cast(errors_thrown())->value();
+}
+
 }  // namespace internal
 }  // namespace v8