Issue 5586 (Use DOM Mutation Observers for MutationRecognize)
Part 1: Replaced mutation events by mutation observer in
MutationRecognizer
Renamed MutationEventFilter to MutationFilter, moved the callback
handler to MutationRecognizer and added JSDocs (related to issue 5586)
Adjusted MutationRecognizer to be able to recognize nested elements
Fixed class check in mutation filter (related to issue 5586)
Always check for changed child elements (related to issue 5586)