remove most uses of raw handle constructors

src/mksnapshot.cc

Index: src/mksnapshot.cc
diff --git a/src/mksnapshot.cc b/src/mksnapshot.cc
index 978ea217bd9e4af37d25bebc8f4d031f70c3a0d4..7c2e1c83b045ad95ffe83d37d57ef86fcd7873d5 100644
--- a/src/mksnapshot.cc
+++ b/src/mksnapshot.cc
@@ -387,7 +387,7 @@ int main(int argc, char** argv) {
   // If we don't do this then we end up with a stray root pointing at the
   // context even after we have disposed of the context.
   HEAP->CollectAllGarbage(i::Heap::kNoGCFlags, "mksnapshot");
-  i::Object* raw_context = *(v8::Utils::OpenHandle(*context));
+  i::Object* raw_context = *v8::Utils::OpenPersistent(context);
   context.Dispose(isolate);
   CppByteSink sink(argv[1]);
   // This results in a somewhat smaller snapshot, probably because it gets rid