use subplot ref in scatterternary hover pointData

... instead of hacky subplot ref punched during ScatterPolar.plot

Author: etpinard

src/traces/scatterternary/hover.js

@@ -50,7 +50,7 @@ module.exports = function hoverPoints(pointData, xval, yval, hovermode) {
     // TODO: nice formatting, and label by axis title, for a, b, and c?
 
     var trace = newPointData.trace;
-    var ternary = trace._ternary;
+    var ternary = newPointData.subplot;
     var hoverinfo = cdi.hi || trace.hoverinfo;
     var parts = hoverinfo.split('+');
     var text = [];

src/traces/scatterternary/plot.js

@@ -26,10 +26,5 @@ module.exports = function plot(ternary, moduleCalcData) {
         layerClipId: ternary._hasClipOnAxisFalse ? ternary.clipIdRelative : null
     };
 
-    // add ref to ternary subplot object in fullData traces
-    for(var i = 0; i < moduleCalcData.length; i++) {
-        moduleCalcData[i][0].trace._ternary = ternary;
-    }
-
     scatterPlot(ternary.graphDiv, plotinfo, moduleCalcData);
 };

test/jasmine/tests/scatterternary_test.js

@@ -332,7 +332,8 @@ describe('scatterternary hover', function() {
             cd: cd[0],
             trace: cd[0][0].trace,
             xa: ternary.xaxis,
-            ya: ternary.yaxis
+            ya: ternary.yaxis,
+            subplot: ternary
         };
 
         return ScatterTernary.hoverPoints(pointData, xval, yval, hovermode);