add a few DRY up TODOs

Author: etpinard

src/plots/cartesian/dragbox.js

@@ -715,6 +715,7 @@ function makeDragBox(gd, plotinfo, x, y, w, h, ns, ew) {
 
         // clear gl frame, if any, since we preserve drawing buffer
         // FIXME: code duplication with cartesian.plot
+        // TODO DRY this up!!
         if(fullLayout._glcanvas && fullLayout._glcanvas.size()) {
             fullLayout._glcanvas.each(function(d) {
                 if(d.regl) d.regl.clear({color: true});

src/traces/splom/base_plot.js

@@ -93,6 +93,7 @@ function drawGrid(gd) {
     splomGrid.draw();
 }
 
+// this clocks in at ~30ms at 50x50 - we could perf this up!
 function makeGridData(gd) {
     var fullLayout = gd._fullLayout;
     var gs = fullLayout._size;
@@ -170,6 +171,8 @@ function makeGridData(gd) {
     return gridBatches;
 }
 
+// just like in Axes.doTicks but without the loop over traces
+// TODO dry this up
 function showZeroLine(ax) {
     var rng = Lib.simpleMap(ax.range, ax.r2l);
     var p0 = ax.l2p(0);