use coerce hovermode in cartesian defaults

Author: archmoj

src/plots/cartesian/layout_defaults.js

@@ -12,6 +12,7 @@
 var Lib = require('../../lib');
 var Color = require('../../components/color');
 var isUnifiedHover = require('../../components/fx/helpers').isUnifiedHover;
+var handleHoverModeDefaults = require('../../components/fx/hovermode_defaults');
 var Template = require('../../plot_api/plot_template');
 var basePlotLayoutAttributes = require('../layout_attributes');
 
@@ -250,7 +251,7 @@ module.exports = function supplyLayoutDefaults(layoutIn, layoutOut, fullData) {
         handleTypeDefaults(axLayoutIn, axLayoutOut, coerce, defaultOptions);
         handleAxisDefaults(axLayoutIn, axLayoutOut, coerce, defaultOptions, layoutOut);
 
-        var hovermode = layoutOut.hovermode || layoutIn.hovermode;
+        var hovermode = handleHoverModeDefaults(layoutIn, layoutOut, fullData);
         var unifiedHover = isUnifiedHover(hovermode);
         var unifiedSpike = unifiedHover && axLetter === hovermode.charAt(0);
         var spikecolor = coerce2('spikecolor', unifiedHover ? axLayoutOut.color : undefined);