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::IncrementExceptionsThrown() {
+  if (!IsNativeContext()) return;

[jochen (gone - plz use gerrit), 2015/10/29 14:37:07]

just DCHECK(IsNativeContext())

[Michael Hablich, 2015/10/29 15:23:34]

Done.

+  if (exceptions_thrown()->IsUndefined()) {

[jochen (gone - plz use gerrit), 2015/10/29 14:37:07]

just initialize exceptions_thrown() to 0 in Factory::NewNativeContext

[Michael Hablich, 2015/10/29 15:23:34]

Done.

+    set_exceptions_thrown(Smi::FromInt(1));
+    return;
+  }
+
+  int previous_value = Smi::cast(exceptions_thrown())->value();
+  set_exceptions_thrown(Smi::FromInt(previous_value+1));
+}
+
+
+int Context::GetExceptionsThrown() {
+  // return -1 so we can identify stats by non-native contexts
+  if (!IsNativeContext()) return -1;

[jochen (gone - plz use gerrit), 2015/10/29 14:37:07]

should never happen

[Michael Hablich, 2015/10/29 15:23:34]

Done.

+  if (exceptions_thrown()->IsUndefined()) {
+    return 0;
+  }
+
+  return Smi::cast(exceptions_thrown())->value();
+}
+
 }  // namespace internal
 }  // namespace v8