Offset repeating theads correctly when two tables adjoin at a page border

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

Index: third_party/WebKit/Source/core/layout/LayoutTable.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutTable.cpp b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
index 38961ef6b09c737491c0767b5d21aab5a27c0e4a..b890f002648075ffad205773aa75642df8de8f0f 100644
--- a/third_party/WebKit/Source/core/layout/LayoutTable.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutTable.cpp
@@ -543,9 +543,13 @@ void LayoutTable::layout()
             section->setLogicalTop(logicalOffset);
             section->layoutRows();
             logicalOffset += section->logicalHeight();
-            if (isPaginated && m_head && m_head == section && section->logicalHeight() < section->pageLogicalHeightForOffset(logicalOffset)) {
+            // If the section is a repeating header group that allows at least one row of content then store the
+            // offset for other sections to offset their rows against.
+            if (isPaginated && m_head && m_head == section && section->logicalHeight() < section->pageLogicalHeightForOffset(logicalOffset)
+                && section->getPaginationBreakability() != LayoutBox::AllowAnyBreaks) {
                 LayoutUnit offsetForTableHeaders = state.heightOffsetForTableHeaders();
-                offsetForTableHeaders += section->logicalHeight();
+                // Don't include any strut in the header group - we only want the height from its content.
+                offsetForTableHeaders += section->logicalHeight() - section->paginationStrutForRow(section->firstRow(), section->logicalTop());

[mstensho (USE GERRIT), 2016/08/10 09:42:48]

section->firstRow() may be nullptr.

                 state.setHeightOffsetForTableHeaders(offsetForTableHeaders);
             }
         }