Remove type="text/javascript" from script tags.

"text/javascript" is not a correct MIME type (the correct one is
"application/javascript") but it's not even needed; all browsers default
to the correct type and treat it as executable JS when type is ommited.
Since not all browsers recognize the "application/javascript" MIME type
the only way to both stay compliant and to support all popular browsers
is to omit the type. It's also shorter this way.
Merge pull request #4782 from mzgol/script-type

Remove type="text/javascript" from script tags.