[css-grid] Fix simplified layout of positioned grid items

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

Index: third_party/WebKit/Source/core/layout/LayoutGrid.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
index 05a01b709fbfee65abbd54397c163e4667c2d148..5c7b314650e7ed0cd63af93142f3511fa9b5feb4 100644
--- a/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutGrid.cpp
@@ -475,7 +475,10 @@ void LayoutGrid::repeatTracksSizingIfNeeded(GridSizingData& sizingData,
 void LayoutGrid::layoutBlock(bool relayoutChildren) {
   ASSERT(needsLayout());
 
-  if (!relayoutChildren && simplifiedLayout())
+  // We cannot perform a simplifiedLayout() on a dirty grid that
+  // has positioned items to be layout.

[mstensho (USE GERRIT), 2016/11/04 09:47:34]

"to be laid out"

[Manuel Rego, 2016/11/04 09:57:56]

Acknowledged.

+  if (!relayoutChildren && !(m_gridIsDirty && posChildNeedsLayout()) &&

[mstensho (USE GERRIT), 2016/11/04 09:47:34]

Nit: Augustus de Morgan might write that middle expression as (!m_gridIsDirty ||
!posChildNeedsLayout()), and so would I. :)

[Manuel Rego, 2016/11/04 09:57:56]

Done.

+      simplifiedLayout())
     return;
 
   SubtreeLayoutScope layoutScope(*this);