Fix true/false redraw blocking bug in synchronizer
Fix true/false redraw blocking bug in synchronizer

Fixes #658

pshevtsov/dygraphs,mantyr/dygraphs,danvk/dygraphs,pshevtsov/dygraphs,vhotspur/dygraphs,pshevtsov/dygraphs,petechap/dygraphs,danvk/dygraphs,vhotspur/dygraphs,mantyr/dygraphs,pshevtsov/dygraphs,mantyr/dygraphs,klausw/dygraphs,klausw/dygraphs,mcanthony/dygraphs,klausw/dygraphs,Akiyah/dygraphs,Akiyah/dygraphs,mcanthony/dygraphs,Akiyah/dygraphs,vhotspur/dygraphs,reinert/dygraphs,Akiyah/dygraphs,petechap/dygraphs,danvk/dygraphs,mcanthony/dygraphs,danvk/dygraphs,reinert/dygraphs,klausw/dygraphs,reinert/dygraphs,pshevtsov/dygraphs,mantyr/dygraphs,reinert/dygraphs,petechap/dygraphs,vhotspur/dygraphs,danvk/dygraphs,reinert/dygraphs,vhotspur/dygraphs,mcanthony/dygraphs,klausw/dygraphs,Akiyah/dygraphs,petechap/dygraphs,mantyr/dygraphs,petechap/dygraphs,mcanthony/dygraphs