Fix NewLocalRef, NewGlobalRef to handle cleared weak globals.

We were not checking for null after decoding the reference, this
meant that we incorrectly created null weak global references instead
of returning null.

Issue: 63929
Change-Id: I9159682e6edad8f415ef8144fc13b9aedd2cceb4

1 files changed, 1 insertions, 1 deletions

diff --git a/runtime/thread.cc b/runtime/thread.cc
index bc252deecc..9faa60dbf8 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -1147,7 +1147,7 @@ mirror::Object* Thread::DecodeJObject(jobject obj) const {
     result = Runtime::Current()->GetJavaVM()->DecodeWeakGlobal(const_cast<Thread*>(this), ref);
     if (result == kClearedJniWeakGlobal) {
       // This is a special case where it's okay to return NULL.
-      return NULL;
+      return nullptr;
     }
   }