validate: this with parent, child

[dan-leech]

validate() { this == this.parent[auth.uid].timestamp }
compiles into
".validate": "newData.val() == newData.parent[auth.uid].timestamp"
supposed:
".validate": "newData.val() == newData.parent().child(auth.uid).child('timestamp').val()"

workaround is
validate() { this == this.parent().child(auth.uid).child('timestamp').val() }