border-spacing is doubled between table-row-groups.

Source/core/rendering/RenderTableSection.cpp

Index: Source/core/rendering/RenderTableSection.cpp
diff --git a/Source/core/rendering/RenderTableSection.cpp b/Source/core/rendering/RenderTableSection.cpp
index de1f54512902e387a152a99808b85479511d81cf..0a2a942edf88f789f24e42774ea876f043f662ad 100644
--- a/Source/core/rendering/RenderTableSection.cpp
+++ b/Source/core/rendering/RenderTableSection.cpp
@@ -511,7 +511,13 @@ int RenderTableSection::calcRowLogicalHeight()
     LayoutStateMaintainer statePusher(viewRenderer);
 
     m_rowPos.resize(m_grid.size() + 1);
-    m_rowPos[0] = table()->vBorderSpacing();
+
+    // Top border spacing of the section is required to add only for the first section in the table.
+    // Because top border spacing of following sections would be bottom border spacing of it's previous section.

[Julien - ping for review, 2013/09/05 17:58:03]

Good comment, let's improve it:

// We ignore the border-spacing on any non-top section as it is already included
in the previous section's last row position.

[a.suchit, 2013/09/06 05:27:18]

Done.

+    if (this == table()->topSection())
+        m_rowPos[0] = table()->vBorderSpacing();
+    else
+        m_rowPos[0] = 0;
 
     SpanningRenderTableCells rowSpanCells;