Filtering by non-trivial Painless scripted fields results in "compile error"

[tbragin]

ES/Kibana version:
5.0.0 running in Elastic Cloud

Browser version:
Chrome Version 54.0.2840.87 (64-bit) on MacOS El Capitan

Description of the problem including expected versus actual behavior:
Filtering by some scripted fields in Discover, Visualize, or Dashboard returns a compile error, while preview in Discover and aggregations in Visualize work.

Steps to reproduce:

1. Create scripted field with one of the values below
2. Filter on this scripted field
3. Observe compile errors come back from Elasticsearch

Sample scripted fields that don't work

Note: This is with data from the getting started tutorial. https://www.elastic.co/guide/en/kibana/current/tutorial-load-dataset.html

LocalDateTime.ofInstant(Instant.ofEpochMilli(doc['@timestamp'].value), ZoneId.of('Z')).getDayOfWeek().getDisplayName(TextStyle.FULL, Locale.getDefault());

Note: Removing semicolon from the expression above gets rid of the filter problem.

if (doc['referer.keyword'].value =~ /error/) { 
return "error"
} else {
return "no error"
}

def m = /^.*\.([a-z]+)$/.matcher(doc['host.keyword'].value);
if ( m.matches() ) {
   return m.group(1)
} else {
   return "no match"
}

Errors in browser console (if relevant):
No browser console errors

[epixa]

When this gets closed, we'll likely need also need to remove the note that we added in #9090

[tbragin]

Now that this is merged in ES, we can address this specifically for Painless: elastic/elasticsearch#21635