V8ValueConverter::ToV8Value should not trigger setters

BUG=606390

Review URL: https://codereview.chromium.org/1918793003

Cr-Commit-Position: refs/heads/master@{#390045}
  static base::Value* NewReferenceValue() {
    return new base::StringValue("strategy");
  }

  static base::Value* NewReferenceValue() {
    return new base::StringValue("strategy");
  }
