Merge 158839 "Reverse style resolution to avoid N^2 walk when bu..."

Source/core/rendering/RenderRegion.cpp

Index: Source/core/rendering/RenderRegion.cpp
===================================================================
--- Source/core/rendering/RenderRegion.cpp	(revision 159683)
+++ Source/core/rendering/RenderRegion.cpp	(working copy)
@@ -550,7 +550,7 @@
 
 void RenderRegion::computeChildrenStyleInRegion(const RenderObject* object)
 {
-    for (RenderObject* child = object->firstChild(); child; child = child->nextSibling()) {
+    for (RenderObject* child = object->lastChild(); child; child = child->previousSibling()) {
 
         RenderObjectRegionStyleMap::iterator it = m_renderObjectRegionStyle.find(child);
 
@@ -602,7 +602,7 @@
     m_renderObjectRegionStyle.remove(object);
 
     // Clear the style for the children of this object.
-    for (RenderObject* child = object->firstChild(); child; child = child->nextSibling())
+    for (RenderObject* child = object->lastChild(); child; child = child->previousSibling())
         clearObjectStyleInRegion(child);
 }