LP#1350042 browser unit tests use repo fm_IDL2js.xsl

Generate JS-friendly IDL2js for browser client unit tests from the .xsl
file within the repo instead of referencing the installed version, which
may not yet exist on the machine.

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Jason Etheridge <jason@esilibrary.com>