Introduce object visitor to estimate the size of a native context.

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 2b874ac4885e2c84c61e0d6cf88556c120435f0c..6cab5b401b09daba5d469cc623dacde6d20fc08e 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -392,6 +392,7 @@ StartupData V8::CreateSnapshotDataBlob(const char* custom_source) {
       // context even after we have disposed of the context.
       internal_isolate->heap()->CollectAllAvailableGarbage("mksnapshot");
       i::Object* raw_context = *v8::Utils::OpenPersistent(context);
+

[jochen (gone - plz use gerrit), 2015/08/05 11:39:46]

nit. remove

       context.Reset();
 
       i::SnapshotByteSink snapshot_sink;