Add grid/flex layout support for <fieldset>

third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp

Index: third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
index 5499abfa2bb724aa3ef6aa575a1d009780070f0c..86e675a59d17499903582d68ed9d1edfea84d88c 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFlexibleBox.cpp
@@ -883,7 +883,7 @@ void LayoutFlexibleBox::layoutFlexItems(bool relayoutChildren, SubtreeLayoutScop
 
     m_orderIterator.first();
     LayoutUnit crossAxisOffset = flowAwareBorderBefore() + flowAwarePaddingBefore();
-    while (computeNextFlexLine(orderedChildren, sumFlexBaseSize, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink, sumHypotheticalMainSize, relayoutChildren)) {
+    while (computeNextFlexLine(orderedChildren, sumFlexBaseSize, totalFlexGrow, totalFlexShrink, totalWeightedFlexShrink, sumHypotheticalMainSize, relayoutChildren, layoutScope)) {
         LayoutUnit containerMainInnerSize = mainAxisContentExtent(sumHypotheticalMainSize);
         // availableFreeSpace is the initial amount of free space in this flexbox.
         // remainingFreeSpace starts out at the same value but as we place and lay out
@@ -1200,7 +1200,7 @@ LayoutUnit LayoutFlexibleBox::adjustChildSizeForAspectRatioCrossAxisMinAndMax(co
     return childSize;
 }
 
-bool LayoutFlexibleBox::computeNextFlexLine(OrderedFlexItemList& orderedChildren, LayoutUnit& sumFlexBaseSize, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink, LayoutUnit& sumHypotheticalMainSize, bool relayoutChildren)
+bool LayoutFlexibleBox::computeNextFlexLine(OrderedFlexItemList& orderedChildren, LayoutUnit& sumFlexBaseSize, double& totalFlexGrow, double& totalFlexShrink, double& totalWeightedFlexShrink, LayoutUnit& sumHypotheticalMainSize, bool relayoutChildren, SubtreeLayoutScope& layoutScope)
 {
     orderedChildren.clear();
     sumFlexBaseSize = LayoutUnit();
@@ -1214,7 +1214,16 @@ bool LayoutFlexibleBox::computeNextFlexLine(OrderedFlexItemList& orderedChildren
 
     bool lineHasInFlowItem = false;
 
+    // Fieldsets need to find their legend and position it inside the border of the object.
+    // The legend then gets skipped during normal layout.
+    // It doesn't get included in the normal layout process but is instead skipped.
+    LayoutObject* childToExclude = layoutSpecialExcludedChild(relayoutChildren, layoutScope);

[cbiesinger, 2016/07/20 01:42:31]

Thanks for doing this! I'll take a closer look tomorrow but briefly, I don't
think calling this inside this function works because we call it (potentially)
multiple times during layout of a single flexbox, whereas we probably only want
to layout the special excluded child once. I would call it from layoutFlexItems
and then just pass in the LayoutObject to this function so we can then skip it.

[Gleb Lanbin, 2016/07/21 18:25:31]

Done.

+
     for (LayoutBox* child = m_orderIterator.currentChild(); child; child = m_orderIterator.next()) {
+
+        if (childToExclude == child)
+            continue; // Skip this child, since it will be positioned by the specialized subclass (fieldsets runs).
+
         if (child->isOutOfFlowPositioned()) {
             orderedChildren.append(FlexItem(child));
             continue;