https://bugs.webkit.org/show_bug.cgi?id=127021
-and corresponding-
<rdar://problem/15571300>

Reviewed by Simon Fraser.

This patch makes repeating background images continue into margin tiles. 

RenderObject::repaintRectangle() now takes an addition bool parameter which 
indicates whether or not the repaint rect should be clipped to the layer size.
* WebCore.exp.in:

These new functions on FrameView provide a way for code in the render tree to know 
if the TiledBacking has a margin. tiledBacking() is now const. It should have 
always been const, and it needs to be const to make these new functions const.
* page/FrameView.cpp:
(WebCore::FrameView::tiledBacking):
(WebCore::FrameView::hasExtendedBackground):
(WebCore::FrameView::extendedBackgroundRect):
* page/FrameView.h:
* platform/ScrollableArea.h:
(WebCore::ScrollableArea::tiledBacking):

If we’re painting the root background and it is an extended background, we need to 
inflate the repaint rect to span the extended background. 
* rendering/RenderBox.cpp:
(WebCore::RenderBox::repaintLayerRectsForImage):

To get the phase right on repeated background images on a page with margin tiles, 
we need to make sure we factor the size of the margin tiles into the left and top 
values that we use when calculating background image geometry.
* rendering/RenderBoxModelObject.cpp:
(WebCore::RenderBoxModelObject::calculateBackgroundImageGeometry):

setBackingNeedsRepaintInRect() now takes GraphicsLayer::ShouldClipToLayer as a 
parameter, just like setBackingNeedsRepaint(). 
* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::calculateClipRects):

setContentsNeedDisplayInRect() also takes a GraphicsLayer::ShouldClipToLayer now, 
and it passes that information down to the GraphicsLayer.
* rendering/RenderLayer.h:
* rendering/RenderLayerBacking.cpp:
(WebCore::RenderLayerBacking::setContentsNeedDisplayInRect):
* rendering/RenderLayerBacking.h:

These two RenderObject functions now take an optional bool parameter which 
indicates whether or not the rect should be clipped to the layer size. They use a 
bool instead of the GraphicsLayer enum in order to avoid including GraphicsLayer.h 
from within RenderObject.h. This seems like a simpler solution than adding a new 
stand-alone file for this very simple enum.
* rendering/RenderObject.cpp:
(WebCore::RenderObject::repaintUsingContainer):
(WebCore::RenderObject::repaintRectangle):
* rendering/RenderObject.h:

RenderView::backgroundRect needs to return the extendedBackgroundRect when it had 
one.
* rendering/RenderView.cpp:
(WebCore::RenderView::backgroundRect):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162098 268f45cc-cd09-0410-ab3c-d52691b4dbfc