Merge 120862

Source/WebCore/rendering/RenderBox.cpp

Index: Source/WebCore/rendering/RenderBox.cpp
===================================================================
--- Source/WebCore/rendering/RenderBox.cpp	(revision 122128)
+++ Source/WebCore/rendering/RenderBox.cpp	(working copy)
@@ -134,24 +134,17 @@
 {
     clearOverrideSize();
 
-    RenderStyle* styleToUse = style();
-    if (styleToUse && (styleToUse->logicalHeight().isPercent() || styleToUse->logicalMinHeight().isPercent() || styleToUse->logicalMaxHeight().isPercent()))
-        RenderBlock::removePercentHeightDescendant(this);
+    if (style()) {
+        RenderBlock::removePercentHeightDescendantIfNeeded(this);
 
-    if (styleToUse) {
         if (RenderView* view = this->view()) {
             if (FrameView* frameView = view->frameView()) {
-                if (styleToUse->position() == FixedPosition)
+                if (style()->position() == FixedPosition)
                     frameView->removeFixedObject(this);
             }
         }
     }
 
-    // If the following assertion fails, logicalHeight()/logicalMinHeight()/
-    // logicalMaxHeight() values are changed from a percent value to a non-percent
-    // value during laying out. It causes a use-after-free bug.
-    ASSERT(!RenderBlock::hasPercentHeightDescendant(this));
-
     RenderBoxModelObject::willBeDestroyed();
 }
 
@@ -232,12 +225,16 @@
 
 void RenderBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
 {
+    // Horizontal writing mode definition is updated in RenderBoxModelObject::updateBoxModelInfoFromStyle,
+    // (as part of the RenderBoxModelObject::styleDidChange call below). So, we can safely cache the horizontal
+    // writing mode value before style change here.
+    bool oldHorizontalWritingMode = isHorizontalWritingMode();
+
     RenderBoxModelObject::styleDidChange(diff, oldStyle);
 
     RenderStyle* newStyle = style();
     if (needsLayout() && oldStyle) {
-        if (oldStyle && (oldStyle->logicalHeight().isPercent() || oldStyle->logicalMinHeight().isPercent() || oldStyle->logicalMaxHeight().isPercent()))
-            RenderBlock::removePercentHeightDescendant(this);
+        RenderBlock::removePercentHeightDescendantIfNeeded(this);
 
         // Normally we can do optimized positioning layout for absolute/fixed positioned objects. There is one special case, however, which is
         // when the positioned object's margin-before is changed. In this case the parent has to get a layout in order to run margin collapsing
@@ -247,6 +244,10 @@
             parent()->setChildNeedsLayout(true);
     }
 
+    if (RenderBlock::hasPercentHeightContainerMap() && firstChild()
+        && oldHorizontalWritingMode != isHorizontalWritingMode())
+        RenderBlock::clearPercentHeightDescendantsFrom(this);
+
     // If our zoom factor changes and we have a defined scrollLeft/Top, we need to adjust that value into the
     // new zoomed coordinate space.
     if (hasOverflowClip() && oldStyle && newStyle && oldStyle->effectiveZoom() != newStyle->effectiveZoom()) {