Use C++11 range-based loop for core/layout

Source/core/layout/LayoutTableSection.cpp

Index: Source/core/layout/LayoutTableSection.cpp
diff --git a/Source/core/layout/LayoutTableSection.cpp b/Source/core/layout/LayoutTableSection.cpp
index 9b371393a1763648621018032f6892d064680463..2a56e6d45398cac51ff9a9bbb62ba032f846000b 100644
--- a/Source/core/layout/LayoutTableSection.cpp
+++ b/Source/core/layout/LayoutTableSection.cpp
@@ -999,9 +999,8 @@ void LayoutTableSection::layoutRows()
 
             if (!cellChildrenFlex) {
                 if (TrackedRendererListHashSet* percentHeightDescendants = cell->percentHeightDescendants()) {
-                    TrackedRendererListHashSet::iterator end = percentHeightDescendants->end();
-                    for (TrackedRendererListHashSet::iterator it = percentHeightDescendants->begin(); it != end; ++it) {
-                        if (flexAllChildren || shouldFlexCellChild(*it)) {
+                    for (auto* descendant : *percentHeightDescendants) {
+                        if (flexAllChildren || shouldFlexCellChild(descendant)) {
                             cellChildrenFlex = true;
                             break;
                         }