Cache RenderStyle pointer as a method to avoid performance regression for region...

Cache RenderStyle pointer as a method to avoid performance regression for region styling
https://bugs.webkit.org/show_bug.cgi?id=76265

Reviewed by David Hyatt.

No new tests since this is just refactoring.
When region styling was enabled in https://bugs.webkit.org/show_bug.cgi?id=71488,
it introduced a performance regression due to the change of RenderObject::style() method.
This patch tries to avoid a new performance regression when region styling will be enabled again.

* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::MarginInfo::MarginInfo):
(WebCore::RenderBlock::styleWillChange):
(WebCore::RenderBlock::layoutBlock):
(WebCore::RenderBlock::layoutBlockChildren):
(WebCore::RenderBlock::layoutBlockChild):
(WebCore::RenderBlock::computePreferredLogicalWidths):
(WebCore::getBorderPaddingMargin):
(WebCore::RenderBlock::computeInlinePreferredLogicalWidths):
(WebCore::RenderBlock::computeBlockPreferredLogicalWidths):
* rendering/RenderBlockLineLayout.cpp:
(WebCore::RenderBlock::layoutRunsAndFloatsInRange):
(WebCore::RenderBlock::LineBreaker::nextLineBreak):
* rendering/RenderBox.cpp:
(WebCore::RenderBox::willBeDestroyed):
(WebCore::RenderBox::styleWillChange):
(WebCore::RenderBox::styleDidChange):
(WebCore::RenderBox::updateBoxModelInfoFromStyle):
(WebCore::RenderBox::computeRectForRepaint):
(WebCore::RenderBox::computeLogicalWidthInRegion):
(WebCore::RenderBox::computeLogicalWidthUsing):
(WebCore::RenderBox::computeLogicalHeight):
(WebCore::RenderBox::computePercentageLogicalHeight):
(WebCore::RenderBox::computePositionedLogicalHeight):
* rendering/RenderBoxModelObject.cpp:
(WebCore::RenderBoxModelObject::styleWillChange):
(WebCore::RenderBoxModelObject::updateBoxModelInfoFromStyle):
* rendering/RenderInline.cpp:
(WebCore::RenderInline::styleDidChange):
* rendering/RenderText.cpp:
(WebCore::RenderText::styleDidChange):
(WebCore::RenderText::computePreferredLogicalWidths):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@105394 268f45cc-cd09-0410-ab3c-d52691b4dbfc