Fixes for arguments object in non strict mode

Fixes for arguments object in non strict mode

In non strict mode, the arguments object actually
reflects the argument as it changes over the lifetime
of a function, unless you explicitly delete some of it's
properties.

The code to implement this is pretty ugly, but still better
then the specification :)

Change-Id: Ie42ed25c797513615fbc4bdee14145d953f323f3
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>