getHighlightsRequest method
Return the highlighting request that should be passes to the contributors returned from getHighlightsContributors.
Throw a RequestFailure if the request could not be created.
Implementation
@override
Future<HighlightsRequest> getHighlightsRequest(String path) async {
var result = await getResolvedUnitResult(path);
return DartHighlightsRequestImpl(resourceProvider, result);
}