Remove frame flattening from rendering code.

Remove frame flattening from rendering code.

Chromium never enables frame flattening; we can simplify frame rendering by
removing the various paths that only execute if flattening is enabled.

Currently, this patch leaves RenderFrameBase as an empty shell. We can probably
remove that entirely in a subsequent patch.

BUG=231902

[Mike West, 2013-04-16 14:48:26]

Hi Ojan, Eric,

Would you lovely folks mind taking a quick look at this patch, which (in theory)
kills off flattened frames from the rendering layer? I'd appreciate it!

-mike

[Mike West, 2013-04-16 14:50:04]

On 2013/04/16 14:48:26, Mike West (chromium) wrote:
> Hi Ojan, Eric,
> 
> Would you lovely folks mind taking a quick look at this patch, which (in
theory)
> kills off flattened frames from the rendering layer? I'd appreciate it!
> 
> -mike

(I'll remove the fast/frames/flattening, etc. tests in this patch as well, but
I'm leaving those out of the review for the moment in the interests of
readability)

[ojan, 2013-04-16 18:37:59]

lgtm

I'm sure you know this, but make sure to find the flattening tests that aren't
in frame/flattening as well. There's a handful of other ones listed in
TestExpectations.

It's so awesome that we can remove a layer of subclassing from the frame
heirarchy. Very excited to see out frame code get manageable as we do this and
get rid of Widgets.

https://codereview.chromium.org/13877010/diff/6001/Source/WebCore/page/FrameV...
File Source/WebCore/page/FrameView.cpp (right):

https://codereview.chromium.org/13877010/diff/6001/Source/WebCore/page/FrameV...
Source/WebCore/page/FrameView.cpp:2008: bool isSeamlessDocument = frame() &&
frame()->document() && frame()->document()->shouldDisplaySeamlesslyWithParent();
The code above and below this uses m_frame and m_frame->document() without a
null-check, so I think you can skip both null checks here. Then you don't really
need the local variable either.

https://codereview.chromium.org/13877010/diff/6001/Source/WebCore/rendering/R...
File Source/WebCore/rendering/RenderFrameBase.h (right):

https://codereview.chromium.org/13877010/diff/6001/Source/WebCore/rendering/R...
Source/WebCore/rendering/RenderFrameBase.h:36: explicit
RenderFrameBase(Element*);
Maybe add a FIXME to delete this file?

[dglazkov, 2013-04-19 21:53:13]

What happened here? Doesn't look like the patch ever landed.

[jamesr, 2013-04-19 22:06:20]

On 2013/04/19 21:53:13, Dimitri Glazkov wrote:
> What happened here? Doesn't look like the patch ever landed.

There was a revert here: https://codereview.chromium.org/14057012/