user32/tests: Show that Windows avoids creating loops in a menu tree, probably by limiting the depth of such tree.

Previously after initial window creation of a richedit control with the
ES_DISABLENOSCROLL window style flag the scrollbar would be shown but
not disabled.  This patch fixes this issue by explicitly disabling and
showing the scrollbar.

Apparently this is an expensive operation for certain drivers, even if the
binding doesn't actually change.

When the richedit control is created without the ES_AUTOHSCROLL or the
ES_AUTOVSCROLL, then scrolling isn't done automatically when moving the
cursor with the arrow keys, drag selecting with the mouse, or even from
using the EM_SCROLLCARET (based on testing using a modified version of
wordpad).

wininet: Rename WININET_strdup_AtoW to heap_strdupAtoW and handle NULL argument in its implementation.

This is for SM4 constant buffers, which look like cb<x>[<y>]. At some later
point we should probably translate pre-SM4 constants to constant buffers.