Fix the charts in the statistics channel

Fix the charts in the statistics channel

The statistics channel's HTML presentation has charts, but it has
a couple of problems.

1. Because of an inconsistent condition, a chart's JS code might have
   been executed, while the HTML markup wasn't present, and this is
   causing a JS error.
2. The feature is turned off on Mozilla-based browsers.

Fix the inconsistency in conditions, remove the conditional rendering
which disabled the feature for Mozilla-based browsers by looking at
the XSLT processor's name, and fix indentation inconsistencies.