Only block container children support pagination struts.

Source/core/layout/LayoutBlockFlow.cpp

Index: Source/core/layout/LayoutBlockFlow.cpp
diff --git a/Source/core/layout/LayoutBlockFlow.cpp b/Source/core/layout/LayoutBlockFlow.cpp
index a4cb56f6fa16a237ad5bf135bd997928c4bebbdc..90095513311596801ffb809105021048486e268c 100644
--- a/Source/core/layout/LayoutBlockFlow.cpp
+++ b/Source/core/layout/LayoutBlockFlow.cpp
@@ -783,7 +783,17 @@ static inline bool shouldSetStrutOnBlock(const LayoutBlockFlow& block, const Roo
     }
     // If we want to break before the block, one final check is needed, since some block object

[leviw_travelin_and_unemployed, 2015/09/22 17:20:31]

This is no longer one final check, and is really trying to say something similar
to what you're saying below (but better).

[mstensho (USE GERRIT), 2015/09/22 18:11:50]

I shuffled things around a little bit, hopefully to your liking. :)

     // types cannot handle struts.
-    return wantsStrutOnBlock && !block.isOutOfFlowPositioned() && !block.isTableCell();
+    if (!wantsStrutOnBlock)
+        return false;
+    if (block.isOutOfFlowPositioned())

[leviw_travelin_and_unemployed, 2015/09/22 17:20:31]

Combine this with the above?

[mstensho (USE GERRIT), 2015/09/22 18:11:50]

Done.

+        return false;
+    // The block needs to be contained by a block container (and not e.g. a flexbox, or a table
+    // (which would be the case if the block is a table cell or table caption)). The reason for
+    // this limitation is simply that block container child layout code is the only place where we

[leviw_travelin_and_unemployed, 2015/09/22 17:20:31]

as you imply in your description, block container here is a block flow in Blink
jargon, no? I'd use that language for consistency.

[mstensho (USE GERRIT), 2015/09/22 18:11:50]

Yeah, "block container" is CSS sp33k. Changing to native sp33k.

+    // pick up the struts and handle them. We could do so in other layout modes as well, but
+    // currently we don't.
+    LayoutBlock* containingBlock = block.containingBlock();
+    return containingBlock && containingBlock->isLayoutBlockFlow();
 }
 
 void LayoutBlockFlow::adjustLinePositionForPagination(RootInlineBox& lineBox, LayoutUnit& delta)