https://bugs.webkit.org/show_bug.cgi?id=116319

Source/WebCore:

Reviewed by Darin Adler.

The optimization added in r102952 was incorrect in the case where a style change
resulted in a positioned-movement-only layout but also required a repaint; it assumed
that a composited layer did not need to be repainted for a a positioned-movement-only layout.

Fix by making RenderObject::setNeedsLayoutForPositionedMovement() check whether the
style change requires a repaint, and calling setLayerNeedsFullRepaint() in that situation.

Test: compositing/repaint/positioned-movement.html

* rendering/RenderLayer.h: RepaintStatus values do not need to be bit flags.
* rendering/RenderObject.cpp:
(WebCore::RenderObject::setStyle): Pass the old style to setNeedsPositionedMovementLayout().
(WebCore::RenderObject::styleDidChange): Ditto.
* rendering/RenderObject.h:
(WebCore::RenderObject::setNeedsPositionedMovementLayout): Now takes a const RenderStyle*.
* rendering/style/RenderStyle.cpp:
(WebCore::RenderStyle::diff): Remove a comment now that this bug is fixed.
(WebCore::RenderStyle::diffRequiresRepaint): Public wrapper for changeRequiresRepaint().
That function never uses contextSensitiveProperties so we can safely ignore them.
* rendering/style/RenderStyle.h: Expose a way to call changeRequiresRepaint().

LayoutTests:

Reviewed by Darin Adler.

Test that does a positioned-movement-only layout and dumps a layer tree with
repaint rects.

* compositing/repaint/positioned-movement-expected.txt: Added.
* compositing/repaint/positioned-movement.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@151622 268f45cc-cd09-0410-ab3c-d52691b4dbfc