js/Makefile.am: Fix dependency generation with srcdir != builddir

If reusing an existing separate builddir, the generation of dependencies
for the JS resource file would fail because it couldn't find misc/config.js,
resulting in the resource file not being regenerated.

https://bugzilla.gnome.org/show_bug.cgi?id=732348
Scripting: exit if the perf script throws an error during collection

If an exception occurs while collecting parameters, exit rather than
just leaving the shell running in the main loop.

https://bugzilla.gnome.org/show_bug.cgi?id=732349
perf: fix bug in code to print out metrics

We don't normally hit the code in scripting.js to print metrics
because shell-perf-tool bypasses it, but there was a left-over
in the code that no longer works. Also add in the units to the
output.

https://bugzilla.gnome.org/show_bug.cgi?id=732349
Scripting.createTestWindow(): take params

Take a parameter object rather than a long parameter list containing
multiple booleans.

https://bugzilla.gnome.org/show_bug.cgi?id=732349
Scripting: catch errors from shell-perf-helper

When calling remote D-Bus methods, handle exceptions, log them
and exit, rather than just proceeding as if nothing happened.

https://bugzilla.gnome.org/show_bug.cgi?id=732349