[CSS Regions] Convert regions iterator loops to range-based loops

https://bugs.webkit.org/show_bug.cgi?id=127464

Reviewed by Antti Koivisto.

Replace most of the iterator loops in the region implementation with
range based for loops. The for loops that iterate only over subsets
of collections have not been changed.

Tests: no new tests, this is a refactoring patch.

* dom/WebKitNamedFlow.cpp:
(WebCore::WebKitNamedFlow::firstEmptyRegionIndex):
(WebCore::WebKitNamedFlow::getRegionsByContent):
(WebCore::WebKitNamedFlow::getRegions):
(WebCore::WebKitNamedFlow::getContent):
* inspector/InspectorOverlay.cpp:
(WebCore::buildObjectForCSSRegionsHighlight):
* rendering/RenderFlowThread.cpp:
(WebCore::RenderFlowThread::validateRegions):
(WebCore::RenderFlowThread::updateLogicalWidth):
(WebCore::RenderFlowThread::computeLogicalHeight):
(WebCore::RenderFlowThread::repaintRectangleInRegions):
(WebCore::RenderFlowThread::removeRenderBoxRegionInfo):
(WebCore::RenderFlowThread::logicalWidthChangedInRegionsForBlock):
(WebCore::RenderFlowThread::clearRenderBoxRegionInfoAndCustomStyle):
(WebCore::RenderFlowThread::isAutoLogicalHeightRegionsCountConsistent):
(WebCore::RenderFlowThread::markAutoLogicalHeightRegionsForLayout):
(WebCore::RenderFlowThread::markRegionsForOverflowLayoutIfNeeded):
(WebCore::RenderFlowThread::updateRegionsFlowThreadPortionRect):
(WebCore::RenderFlowThread::collectLayerFragments):
(WebCore::RenderFlowThread::fragmentsBoundingBox):
* rendering/RenderNamedFlowFragment.cpp:
(WebCore::RenderNamedFlowFragment::setRegionObjectsRegionStyle):
(WebCore::RenderNamedFlowFragment::restoreRegionObjectsOriginalStyle):
* rendering/RenderNamedFlowThread.cpp:
(WebCore::RenderNamedFlowThread::clearContentElements):
(WebCore::RenderNamedFlowThread::nextRendererForNode):
(WebCore::RenderNamedFlowThread::dependsOn):
(WebCore::RenderNamedFlowThread::computeOversetStateForRegions):
(WebCore::RenderNamedFlowThread::checkInvalidRegions):
(WebCore::RenderNamedFlowThread::pushDependencies):
(WebCore::RenderNamedFlowThread::registerNamedFlowContentElement):
(WebCore::isContainedInElements):
(WebCore::RenderNamedFlowThread::getRanges):
(WebCore::RenderNamedFlowThread::checkRegionsWithStyling):
(WebCore::RenderNamedFlowThread::clearRenderObjectCustomStyle):
* rendering/RenderTreeAsText.cpp:
(WebCore::writeRenderRegionList):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@162602 268f45cc-cd09-0410-ab3c-d52691b4dbfc