RenderGrid should include grid items' margins in its intrinsic size

Source/core/rendering/RenderBlock.cpp

Index: Source/core/rendering/RenderBlock.cpp
diff --git a/Source/core/rendering/RenderBlock.cpp b/Source/core/rendering/RenderBlock.cpp
index 67bb4641622faa68fe56127a72f93b7174e017a9..310b51a653d2283715c02ff992274f38868f24f1 100644
--- a/Source/core/rendering/RenderBlock.cpp
+++ b/Source/core/rendering/RenderBlock.cpp
@@ -1952,6 +1952,21 @@ void RenderBlock::markFixedPositionObjectForLayoutIfNeeded(RenderObject* child,
     }
 }
 
+LayoutUnit RenderBlock::marginIntrinsicLogicalWidthForChild(RenderBox* child) const
+{
+    // A margin has three types: fixed, percentage, and auto (variable).
+    // Auto and percentage margins become 0 when computing min/max width.
+    // Fixed margins can be added in as is.
+    Length marginLeft = child->style()->marginStartUsing(style());
+    Length marginRight = child->style()->marginEndUsing(style());
+    LayoutUnit margin = 0;
+    if (marginLeft.isFixed())
+        margin += marginLeft.value();
+    if (marginRight.isFixed())
+        margin += marginRight.value();
+    return margin;
+}
+
 void RenderBlock::layoutPositionedObjects(bool relayoutChildren, bool fixedPositionObjectsOnly)
 {
     TrackedRendererListHashSet* positionedDescendants = positionedObjects();