[LayoutNG] Initial implementation of NGBoxIterator

third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc b/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc
index 944f0a187ac92aa6bda220a91ed0179720a49e96..3e1d1630434f73a56f86d984bc21942213b31d2a 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_block_layout_algorithm.cc
@@ -14,8 +14,8 @@ namespace blink {
 
 NGBlockLayoutAlgorithm::NGBlockLayoutAlgorithm(
     PassRefPtr<const ComputedStyle> style,
-    NGBox firstChild)
-    : m_style(style), m_firstChild(firstChild) {}
+    NGBoxIterator ngBoxIterator)
+    : m_style(style), m_ngBoxIterator(ngBoxIterator) {}
 
 NGFragment* NGBlockLayoutAlgorithm::layout(
     const NGConstraintSpace& constraintSpace) {
@@ -24,7 +24,7 @@ NGFragment* NGBlockLayoutAlgorithm::layout(
   LayoutUnit blockSize = valueForLength(m_style->logicalHeight(),
                                         constraintSpace.blockContainerSize());
 
-  for (NGBox curr = m_firstChild; curr; curr.nextSibling()) {
+  for (NGBox curr = m_ngBoxIterator.first(); curr; m_ngBoxIterator.next()) {
     curr.layout(constraintSpace);
   }