Strip anonymous blocks when change in style removes need for them

Source/core/rendering/RenderBlock.cpp

Index: Source/core/rendering/RenderBlock.cpp
diff --git a/Source/core/rendering/RenderBlock.cpp b/Source/core/rendering/RenderBlock.cpp
index a95ad9ee2a5fb8d4cc81f71a43687feab0881aa4..e12eb65c34c70b4ac03cf0e4e739bd6dd15669cc 100644
--- a/Source/core/rendering/RenderBlock.cpp
+++ b/Source/core/rendering/RenderBlock.cpp
@@ -331,6 +331,9 @@ void RenderBlock::styleDidChange(StyleDifference diff, const RenderStyle* oldSty
 {
     RenderBox::styleDidChange(diff, oldStyle);
 
+    if (isFloatingOrOutOfFlowPositioned() && oldStyle && !oldStyle->isFloating() && !oldStyle->hasOutOfFlowPosition() && parent() && parent()->isRenderBlockFlow())
+        toRenderBlock(parent())->removeAnonymousWrappersIfRequired();
+
     RenderStyle* newStyle = style();
 
     if (!isAnonymousBlock()) {
@@ -1080,6 +1083,26 @@ static bool canMergeContiguousAnonymousBlocks(RenderObject* oldChild, RenderObje
            && prev->isAnonymousColumnSpanBlock() == next->isAnonymousColumnSpanBlock();
 }
 
+void RenderBlock::removeAnonymousWrappersIfRequired()

[esprehn, 2014/05/27 20:05:03]

Should this method be in RenderBlockFlow instead? You check isRenderBlockFlow
above.

+{
+    Vector<RenderBox*> blocksToRemove;

[esprehn, 2014/05/27 20:05:03]

Add inline capacity, I'd go with 8 or 16.

+    RenderBox* child = firstChildBox();
+    while (child) {
+        // There are still block children in the container, so any anonymous wrappers are still needed.
+        if (!child->isAnonymousBlock() && !child->isFloatingOrOutOfFlowPositioned())
+            return;
+        // We can't remove anonymous wrappers if they contain continuations as this means there are block children present.
+        if (child->isRenderBlock() && toRenderBlock(child)->continuation())
+            return;
+        if (child->isAnonymousBlock())
+            blocksToRemove.append(child);
+        child = child->nextSiblingBox();

[esprehn, 2014/05/27 20:05:03]

This should be a for() loop now.

+    }
+
+    for (unsigned i = 0; i < blocksToRemove.size(); i++)

[esprehn, 2014/05/27 20:05:03]

size_t

+        collapseAnonymousBlockChild(this, toRenderBlock(blocksToRemove[i]));
+}
+
 void RenderBlock::collapseAnonymousBlockChild(RenderBlock* parent, RenderBlock* child)
 {
     // It's possible that this block's destruction may have been triggered by the