Provide a counter for thrown JavaScript errors per context

src/factory.cc

Index: src/factory.cc
diff --git a/src/factory.cc b/src/factory.cc
index f475efcc7725c72a9179a1b580baae0e44116ecb..5266e9d8c5b27027049e2a59284a78c94e25e20e 100644
--- a/src/factory.cc
+++ b/src/factory.cc
@@ -726,6 +726,10 @@ Handle<Context> Factory::NewNativeContext() {
   array->set_map_no_write_barrier(*native_context_map());
   Handle<Context> context = Handle<Context>::cast(array);
   context->set_js_array_maps(*undefined_value());
+  // Initialize with -1 because the value is incremented once
+  // during the build. This means the value is correctly initialized to
+  // 0 afterwards.
+  context->set_errors_thrown(Smi::FromInt(-1));

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

This seems somewhat brittle.

Could we move this line to bootstrapper.cc Genesis::Genesis, right after this:

isolate->counters()->contexts_created_from_scratch()->Increment();

https://code.google.com/p/chromium/codesearch#chromium/src/v8/src/bootstrappe...

[Michael Hablich, 2015/11/04 10:58:08]

Thanks for the remark. I left the initialization in factory.cc because it should
still create a valid Context. Additionally I re-initialize the the counter when
a context is loaded from the snapshot.

   DCHECK(context->IsNativeContext());
   return context;
 }