Fixed issue with $document bening an array ref not an object

[ivanwills]

The $document appears as if it is meant to be an array ref but on this line is us used as a object, the fix is a best guess at what is meant to happen.

[ingydotnet]

Tried this patch, but it breaks the tests.

Please try again, and possibly add a new test for your fix.

Cheers, Ingy

Failure:

$ prove -lv test/selectors.t 
test/selectors.t .. 
1..23
ok 1 - * finds all
ok 2 - select an element by tag name
Not an ARRAY reference at /home/ingy/src/pquery-pm/lib/pQuery.pm line 74.
# Looks like you planned 23 tests but ran 2.
# Looks like your test exited with 255 just after 2.
Dubious, test returned 255 (wstat 65280, 0xff00)
Failed 21/23 subtests 

Test Summary Report
-------------------
test/selectors.t (Wstat: 65280 Tests: 2 Failed: 0)
Non-zero exit status: 255
Parse errors: Bad plan.  You planned 23 tests but ran 2.
Files=1, Tests=2,  0 wallclock secs ( 0.02 usr  0.01 sys +  0.05 cusr  0.00 csys =  0.08 CPU)
Result: FAIL