Update progress-chart.js (mozilla#4015)

Author: functionzz

pontoon/base/static/js/progress-chart.js

@@ -21,6 +21,7 @@ $(function () {
 
     const fraction = {
         translated: stats.all ? stats.translated / stats.all : 0,
+        pretranslated: stats.all ? stats.pretranslated / stats.all : 0,
         warnings: stats.all ? stats.warnings / stats.all : 0,
         errors: stats.all ? stats.errors / stats.all : 0,
         missing: stats.all