cleanData should modify textposition in place

so as to not muck up plotly.react immutable logic

Author: alexcjohnson

src/plot_api/helpers.js

@@ -283,7 +283,9 @@ exports.cleanData = function(data, existingData) {
 
         if(!Registry.traceIs(trace, 'pie') && !Registry.traceIs(trace, 'bar')) {
             if(Array.isArray(trace.textposition)) {
-                trace.textposition = trace.textposition.map(cleanTextPosition);
+                for(i = 0; i < trace.textposition.length; i++) {
+                    trace.textposition[i] = cleanTextPosition(trace.textposition[i]);
+                }
             }
             else if(trace.textposition) {
                 trace.textposition = cleanTextPosition(trace.textposition);