shdocvw: Partial implementation of WebBrowser_put_RegisterAsBrowser and WebBrowser_get_RegisterAsBrowser.

This reverts commit c8bdebde.
To be revisited after 1.0.

Fixes screen not updating or getting updated inconsistently when apps blit to 
front buffer or lock it when RenderTargetLockMode=readtex, as happens in e.g. 
Red Alert 2 and also in p8_primary_test in ddraw tests.

server: When moving/resizing a window crop the update region against the new rectangle of the parents.