Treat percent-height boxes inside auto-height cells as auto

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

Index: third_party/WebKit/Source/core/layout/LayoutBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutBox.cpp b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
index 405cfa8fa480d7b8e0c57767319f7d3be211aec1..f6ccd57930f409be068da3362a08d745b271de2f 100644
--- a/third_party/WebKit/Source/core/layout/LayoutBox.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutBox.cpp
@@ -2588,10 +2588,14 @@ LayoutUnit LayoutBox::computePercentageLogicalHeight(const Length& height) const
         availableHeight = overrideContainingBlockContentLogicalHeight();
     } else if (cb->isTableCell()) {
         if (!skippedAutoHeightContainingBlock) {
-            // Table cells violate what the CSS spec says to do with heights. Basically we
-            // don't care if the cell specified a height or not. We just always make ourselves
-            // be a percentage of the cell's current content height.
-            if (!cb->hasOverrideLogicalContentHeight()) {
+            // The second clause in this conditional (after the ||) is to support this line from the
+            // definition of height in CSS 2.2:
+            // "If the height of the containing block is not specified explicitly (i.e., it depends on
+            // content height), and this element is not absolutely positioned, the used height is
+            // calculated as if 'auto' was specified."
+            // But FF doesn't apply this logic (1) in quirks mode or (2) when "this element" is a table.
+            // TODO(dgrogan): Maybe we shouldn't make tables an exception. See https://crbug.com/353580
+            if (!cb->hasOverrideLogicalContentHeight() || (!document().inQuirksMode() && !isTable() && cbstyle.logicalHeight().isAuto())) {
                 // Normally we would let the cell size intrinsically, but scrolling overflow has to be
                 // treated differently, since WinIE lets scrolled overflow regions shrink as needed.
                 // While we can't get all cases right, we can at least detect when the cell has a specified