replace false values with BADNUM in empty calcdata traces

Author: etpinard

src/plots/plots.js

@@ -16,6 +16,7 @@ var Plotly = require('../plotly');
 var Registry = require('../registry');
 var Lib = require('../lib');
 var Color = require('../components/color');
+var BADNUM = require('../constants/numerical').BADNUM;
 
 var plots = module.exports = {};
 
@@ -2013,7 +2014,7 @@ plots.doCalcdata = function(gd, traces) {
         // This ensures there is a calcdata item for every trace,
         // even if cartesian logic doesn't handle it (for things like legends).
         if(!Array.isArray(cd) || !cd[0]) {
-            cd = [{x: false, y: false}];
+            cd = [{x: BADNUM, y: BADNUM}];
         }
 
         // add the trace-wide properties to the first point,