hgweb: look up "URLSearchParams" in "window" to work around jshint issues
Unfortunately, current version of jshint (2.9.5) doesn't know such a global
variable and complains that it's undefined. Since this line tries to look up
URLSearchParams in a global scope (i.e. window), let's simply preface it with
"window." to work around jshint.
(binary:application/octet-stream)