message: Fix typo in GraphVisualizer
  Summary: Ternaries work in a certain way...
diff: @@ -235,7 +235,7 @@ class CodeVisualizer : public TaggedBase {
  virtual ~CodeVisualizer() {}
  static void dex_string(std::ostream& os, const DexString* s) {
  - os << (s ? "<null>" : s->str());
  + os << (s ? s->str() : "<null>");
  }
  void instruction(IRInstruction* insn) {
  