Partial fix for T49836: Camera DOF properties not updating via graph editor

Do this for the new dependency graph: was missing handle of OB_UPDATE_TIME in tag update.

Hopefully it's all correct still.

Old dependency graph needs work, but i'm tempting to call it unsupported and move on
to 2.8 branch.

source/blender/depsgraph/intern/depsgraph_tag.cc

@@ -235,6 +235,9 @@ void DEG_id_tag_update_ex(Main *bmain, ID *id, short flag)
 			if (flag & (OB_RECALC_OB | OB_RECALC_DATA)) {
 				DEG_graph_id_tag_update(bmain, graph, id);
 			}
+			else if (flag & OB_RECALC_TIME) {
+				DEG_graph_id_tag_update(bmain, graph, id);
+			}
 		}
 	}