Fix issue in destroy for HTML insets. Fix HTML event handler leaking
Fix issue in destroy for HTML insets. Fix HTML event handler leaking

hms-dbmi/higlass,hms-dbmi/4DN_matrix-viewer,hms-dbmi/higlass,hms-dbmi/higlass,hms-dbmi/4DN_matrix-viewer,hms-dbmi/4DN_matrix-viewer,hms-dbmi/higlass