https://bugs.webkit.org/show_bug.cgi?id=78040

Reviewed by Eric Seidel.

Add pixel snapped versions of x/y/width/height methods. These return the
same value as the x/w/width/height methods for now but once we move over
to sub pixel layout they will snap the subpixel value to a device pixel
and return an integer value.

When snapping the left and top edge is simply rounded to the nearest
device pixel.
The right and bottom edges are computed by subtracting the rounded left/
top edge from the precise location and size. This ensures that the edges
all line up with device pixels and that the total size of an object,
including borders, is at most one pixel off.

In summary, the values are computed as follows:
        x: round(x)
        y: round(y)
        maxX: round(x + width)
        maxY: round(y + height)
        width: round(x + width) - round(x)
        height: round(y + height) - round(y)

We use the term pixel snapped to indicate that the numbers are not merely
rounded. This also matches the naming used by the line box tree.

No new tests, no functionality changes.

* page/PrintContext.cpp:
(WebCore::PrintContext::pageNumberForElement):
* rendering/RenderBlock.cpp:
(WebCore::::collectIfNeeded):
* rendering/RenderBlock.h:
(RenderBlock):
(WebCore::RenderBlock::pixelSnappedLogicalRightOffsetForLine):
(WebCore::RenderBlock::pixelSnappedLogicalLeftOffsetForLine):
(WebCore::RenderBlock::FloatingObject::pixelSnappedX):
(WebCore::RenderBlock::FloatingObject::pixelSnappedMaxX):
(WebCore::RenderBlock::FloatingObject::pixelSnappedY):
(WebCore::RenderBlock::FloatingObject::pixelSnappedMaxY):
(WebCore::RenderBlock::FloatingObject::pixelSnappedWidth):
(WebCore::RenderBlock::FloatingObject::pixelSnappedHeight):
(FloatingObject):
(WebCore::RenderBlock::pixelSnappedLogicalTopForFloat):
(WebCore::RenderBlock::pixelSnappedLogicalBottomForFloat):
(WebCore::RenderBlock::pixelSnappedLogicalLeftForFloat):
(WebCore::RenderBlock::pixelSnappedLogicalRightForFloat):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::LineWidth::shrinkAvailableWidthForNewFloatIfNeeded):
* rendering/RenderBox.cpp:
(WebCore::RenderBox::pixelSnappedClientWidth):
(WebCore):
(WebCore::RenderBox::pixelSnappedClientHeight):
(WebCore::RenderBox::scrollHeight):
* rendering/RenderBox.h:
(WebCore::RenderBox::pixelSnappedWidth):
(WebCore::RenderBox::pixelSnappedHeight):
(RenderBox):
(WebCore::RenderBox::pixelSnappedOffsetWidth):
(WebCore::RenderBox::pixelSnappedOffsetHeight):
(WebCore::RenderBox::clientLogicalWidth):
(WebCore::RenderBox::clientLogicalHeight):
* rendering/RenderBoxModelObject.cpp:
(WebCore::RenderBoxModelObject::pixelSnappedOffsetWidth):
(WebCore):
(WebCore::RenderBoxModelObject::pixelSnappedOffsetHeight):
* rendering/RenderBoxModelObject.h:
(WebCore::RenderBoxModelObject::pixelSnappedOffsetLeft):
(WebCore::RenderBoxModelObject::pixelSnappedOffsetTop):
(RenderBoxModelObject):
* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::pixelSnappedScrollWidth):
(WebCore):
(WebCore::RenderLayer::pixelSnappedScrollHeight):
(WebCore::RenderLayer::computeScrollDimensions):
(WebCore::RenderLayer::updateScrollInfoAfterLayout):
* rendering/RenderLayer.h:
(RenderLayer):
* rendering/RenderListBox.cpp:
(WebCore::RenderListBox::scrollHeight):
* rendering/RenderTheme.cpp:
(WebCore::RenderTheme::volumeSliderOffsetFromMuteButton):
* rendering/RenderTreeAsText.cpp:
(WebCore::write):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107032 268f45cc-cd09-0410-ab3c-d52691b4dbfc