Implement Layout Containment

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

Index: third_party/WebKit/Source/core/layout/LayoutBlock.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
index ecc2c5f603b3f702b735d680bb7c5d9a35b678e4..72befd142163eec50660fc0a61a10d627f923bf8 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBlock.cpp
@@ -1007,7 +1007,7 @@ bool LayoutBlock::createsNewFormattingContext() const
 {
     return isInlineBlockOrInlineTable() || isFloatingOrOutOfFlowPositioned() || hasOverflowClip() || isFlexItemIncludingDeprecated()
         || style()->specifiesColumns() || isLayoutFlowThread() || isTableCell() || isTableCaption() || isFieldset() || isWritingModeRoot()
-        || isDocumentElement() || isColumnSpanAll() || isGridItem() || style()->containsPaint();
+        || isDocumentElement() || isColumnSpanAll() || isGridItem() || style()->containsPaint() || style()->containsLayout();
 }
 
 void LayoutBlock::updateBlockChildDirtyBitsBeforeLayout(bool relayoutChildren, LayoutBox& child)
@@ -1957,6 +1957,10 @@ int LayoutBlock::columnGap() const
 
 void LayoutBlock::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 {
+    // Layout-contained elements don't consider their contents for preferred sizing.
+    if (style()->containsLayout())
+        return;
+
     if (childrenInline()) {
         // FIXME: Remove this const_cast.
         toLayoutBlockFlow(const_cast<LayoutBlock*>(this))->computeInlinePreferredLogicalWidths(minLogicalWidth, maxLogicalWidth);
@@ -2237,8 +2241,11 @@ int LayoutBlock::inlineBlockBaseline(LineDirectionMode lineDirection) const
     // either no in-flow line boxes or if its 'overflow' property has a computed
     // value other than 'visible', in which case the baseline is the bottom
     // margin edge.
+    // We likewise avoid using the last line box in the case of layout containment,
+    // where the block's contents shouldn't be considered when laying out its
+    // ancestors or siblings.
 
-    if (!style()->isOverflowVisible() && !shouldIgnoreOverflowPropertyForInlineBlockBaseline()) {
+    if ((!style()->isOverflowVisible() && !shouldIgnoreOverflowPropertyForInlineBlockBaseline()) || style()->containsLayout()) {

[ojan, 2015/12/18 18:21:14]

I think this is the right behavior, although I'm not confident the current spec
covers this. Might want to run this by Tab. If this is handled by the current
spec, I think it at least deserves an explanatory note.

[leviw_travelin_and_unemployed, 2016/01/12 19:36:31]

I did add some info to the above comment to try and tackle this. My feeling was
the spec does cover this, albeit obliquely. It says the contents shouldn't
effect layout, and this ensures that's the case, and that's what I tried to
elude to. +tabatkins to comment.

         // We are not calling LayoutBox::baselinePosition here because the caller should add the margin-top/margin-right, not us.
         return lineDirection == HorizontalLine ? size().height() + marginBottom() : size().width() + marginLeft();
     }