Be consistent about formatting within 1 and the same file.

If half the file is written in ES6, it is easier to read if the rest of
the file is in ES6 as well. If ES6 is used, then const is better than
let. If source code is shorter yet as readable as the long version, then
prefer the short version.

window.location calls it reload so util/helpers shouldn't call it
redirect because UI/util/UIUtil has it is own redirect which is the
assign of window.location.

Recently, we reimplemented the watermarks in React. Unfortunately, we
didn't take into account film strip-only mode.

Additionally, we duplicated watermark-related source code on the Welcome
and Conference pages.