RenderLayer code

[Lars Knoll]

> The layer code has been changed substantially since Safari v51 (lots of
> bugs fixes).  I can try to get you a patch with changes, or a diff
> relative to v51....  whichever is easiest.

A diff relative to v51 is fine, and if you could append render_layer.cpp and 
render_layer.h aswell, that would make my life even easier.

> > Painting of layers with the same z-index doesn't always honour
> > document order.
> > See for example the fourth test of http://dbaron.org/css/test/sec0909.
>
> Safari passes all tests on that page with the current layer code except
> for test #8.   Test #8 is broken (Mozilla handles it the same way
> Safari does).  Actually even Safari v51 passes all the tests except for
> test #8.  Maybe you're missing the code that sets up auto z-index over
> on the render_style side, or maybe the code in cssstyleselector that
> sets zauto to true?

I've solved the problem a little different (using a magic number for auto to 
avoid making the style object 4 bytes bigger for one bitflag), but it should 
be the same otherwise.

> > www.sport1.de is now broken and doesn't show anything in the
> > scrollable news
> > area anymore. Not sure if this is related to z-index problems.
>
> I don't see anything in the scrollable news area, but I tried with
> Mozilla and also don't see anything in that news area.  (I assume you
> mean that section in about the center of the page with an arrow above
> and below the rectangle?)

Exactly that one. It works in IE and it used to work before I merged in the 
layer code.

Lars