Fix comma errors in various js files (new jshint warning)

Fix comma errors in various js files (new jshint warning)

We're about to upgrade to JSHint 2.x. Among various improvements
it now properly detects incorrect use of the comma operator.

This helped uncover two mistakes that could solve a bug, though
in this case the difference was purely in the semantics. The
endresult is unchanged.

Incorrect use of the comma operator can lead to assigning the
wrong value to a variable or causing an implied global variable.

> $ jshint --version
> jshint v2.1.11
> $ jshint .
> resources/jquery/jquery.textSelection.js: line 298, col 71, Expected an assignment or function call and instead saw an expression.
>
> tests/qunit/suites/resources/mediawiki/mediawiki.util.test.js: line 99, col 44, Expected an assignment or function call and instead saw an expression.
>
> 2 errors

Change-Id: I6fdae5f66ef69b6526121cd7b1b2fbb0d9df7a62