[PATCH] jscript: Fix `this` within IDispatchEx::InvokeEx

[Jacek Caban]

From: Puetz Kevin A <PuetzKevinA(a)JohnDeere.com>

Latent bug revealed by 614ea7e6243ead003bcfe4624895154972f3445f;
Now that cross-context calls go through disp_call* instead of 
jsdisp_call*, and thus through InvokeEx, the `this` pointer is
lost when calling methods inherited from a prototype.

Signed-off-by: Kevin Puetz <PuetzKevinA(a)JohnDeere.com>
Signed-off-by: Jacek Caban <jacek(a)codeweavers.com>
---
  dlls/jscript/dispex.c    |  8 ++--
  dlls/jscript/tests/run.c | 89 +++++++++++++++++++++++++++++++++++++++-
  2 files changed, 92 insertions(+), 5 deletions(-)