use new svgTextUtils.plainText opts for <extra> (aka name) hover label

Author: etpinard

src/components/fx/hover.js

@@ -925,15 +925,10 @@ function createHoverText(hoverData, opts, gd) {
         if(d.nameOverride !== undefined) d.name = d.nameOverride;
 
         if(d.name) {
-            // strip out our pseudo-html elements from d.name (if it exists at all)
-            name = svgTextUtils.plainText(d.name || '');
-
-            var nameLength = Math.round(d.nameLength);
-
-            if(nameLength > -1 && name.length > nameLength) {
-                if(nameLength > 3) name = name.substr(0, nameLength - 3) + '...';
-                else name = name.substr(0, nameLength);
-            }
+            name = svgTextUtils.plainText(d.name || '', {
+                len: d.nameLength,
+                allowedTags: ['br', 'sub', 'sup']
+            });
         }
 
         if(d.zLabel !== undefined) {