[css tables] Don't pass table width increase due to % columns to parents

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

 /*
  * Copyright (C) 2002 Lars Knoll (knoll@kde.org)
  *           (C) 2002 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2006, 2008, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License.
  *
@@ skipping 197 matching lines @@
 
 void TableLayoutAlgorithmAuto::computeIntrinsicLogicalWidths(LayoutUnit& minWidth, LayoutUnit& maxWidth)
 {
     TextAutosizer::TableLayoutScope textAutosizerTableLayoutScope(m_table);
 
     fullRecalc();
 
     int spanMaxLogicalWidth = calcEffectiveLogicalWidth();
     minWidth = LayoutUnit();
     maxWidth = LayoutUnit();
+
+    for (size_t i = 0; i < m_layoutStruct.size(); ++i) {
+        minWidth += m_layoutStruct[i].effectiveMinLogicalWidth;
+        maxWidth += m_layoutStruct[i].effectiveMaxLogicalWidth;
+    }
+
+    maxWidth = LayoutUnit(std::max(maxWidth.floor(), spanMaxLogicalWidth));
+}
+
+LayoutUnit TableLayoutAlgorithmAuto::scaledWidthFromPercentColumns()
+{
+    // Normally, scale all columns to satisfy this from CSS2.2:
+    // "A percentage value for a column width is relative to the table width.
+    // If the table has 'width: auto', a percentage represents a constraint on the column's width"
+    if (!shouldScaleColumns(m_table))
+        return LayoutUnit(0);
+
     float maxPercent = 0;
     float maxNonPercent = 0;
-    bool scaleColumns = shouldScaleColumns(m_table);
 
     // We substitute 0 percent by (epsilon / percentScaleFactor) percent in two places below to avoid division by zero.
     // FIXME: Handle the 0% cases properly.
     const float epsilon = 1 / 128.0f;
 
     float remainingPercent = 100;
     for (size_t i = 0; i < m_layoutStruct.size(); ++i) {
-        minWidth += m_layoutStruct[i].effectiveMinLogicalWidth;

[dgrogan, 2016/04/27 03:14:05]

Your excerpt was instrumental in my understanding of what this loop was doing.
So, thank you again :)

-        maxWidth += m_layoutStruct[i].effectiveMaxLogicalWidth;
-        if (scaleColumns) {
-            if (m_layoutStruct[i].effectiveLogicalWidth.hasPercent()) {
-                float percent = std::min(static_cast<float>(m_layoutStruct[i].effectiveLogicalWidth.percent()), remainingPercent);
-                float logicalWidth = static_cast<float>(m_layoutStruct[i].effectiveMaxLogicalWidth) * 100 / std::max(percent, epsilon);
-                maxPercent = std::max(logicalWidth,  maxPercent);
-                remainingPercent -= percent;
-            } else {
-                maxNonPercent += m_layoutStruct[i].effectiveMaxLogicalWidth;
-            }
+        if (m_layoutStruct[i].effectiveLogicalWidth.hasPercent()) {
+            float percent = std::min(static_cast<float>(m_layoutStruct[i].effectiveLogicalWidth.percent()), remainingPercent);
+            float logicalWidth = static_cast<float>(m_layoutStruct[i].effectiveMaxLogicalWidth) * 100 / std::max(percent, epsilon);
+            maxPercent = std::max(logicalWidth,  maxPercent);
+            remainingPercent -= percent;
+        } else {
+            maxNonPercent += m_layoutStruct[i].effectiveMaxLogicalWidth;
         }
     }
 
-    if (scaleColumns) {
-        maxNonPercent = maxNonPercent * 100 / std::max(remainingPercent, epsilon);
-        maxWidth = std::max(maxWidth, LayoutUnit(std::min(maxNonPercent, static_cast<float>(tableMaxWidth))));
-        maxWidth = std::max(maxWidth, LayoutUnit(std::min(maxPercent, static_cast<float>(tableMaxWidth))));
-    }
-
-    maxWidth = LayoutUnit(std::max(maxWidth.floor(), spanMaxLogicalWidth));
+    maxNonPercent = maxNonPercent * 100 / std::max(remainingPercent, epsilon);
+    LayoutUnit maxWidth = LayoutUnit(std::min(maxNonPercent, static_cast<float>(tableMaxWidth)));
+    return std::max(maxWidth, LayoutUnit(std::min(maxPercent, static_cast<float>(tableMaxWidth))));
 }
 
 void TableLayoutAlgorithmAuto::applyPreferredLogicalWidthQuirks(LayoutUnit& minWidth, LayoutUnit& maxWidth) const
 {
     Length tableLogicalWidth = m_table->style()->logicalWidth();
     if (tableLogicalWidth.isFixed() && tableLogicalWidth.isPositive()) {
         // |minWidth| is the result of measuring the intrinsic content's size. Keep it to
         // make sure we are *never* smaller than the actual content.
         LayoutUnit minContentWidth = minWidth;
         // FIXME: This line looks REALLY suspicious as it could allow the minimum
@@ skipping 435 matching lines @@
             int reduce = available * minMaxDiff / logicalWidthBeyondMin;
             m_layoutStruct[i].computedLogicalWidth += reduce;
             available -= reduce;
             logicalWidthBeyondMin -= minMaxDiff;
             if (available >= 0)
                 break;
         }
     }
 }
 } // namespace blink