Modify supercluster multiplier logic.

Source/core/rendering/FastTextAutosizer.cpp

Index: Source/core/rendering/FastTextAutosizer.cpp
diff --git a/Source/core/rendering/FastTextAutosizer.cpp b/Source/core/rendering/FastTextAutosizer.cpp
index 16d4b55e1689b4cbd4824891b7a71cb8bd5345f1..fa0076113f73d673e516d63b771ff539c2a8c0d2 100644
--- a/Source/core/rendering/FastTextAutosizer.cpp
+++ b/Source/core/rendering/FastTextAutosizer.cpp
@@ -701,23 +701,6 @@ FastTextAutosizer::Supercluster* FastTextAutosizer::getSupercluster(const Render
     return supercluster;
 }
 
-const RenderBlock* FastTextAutosizer::deepestCommonAncestor(BlockSet& blocks)
-{
-    // Find the lowest common ancestor of blocks.
-    // Note: this could be improved to not be O(b*h) for b blocks and tree height h.
-    HashCountedSet<const RenderBlock*> ancestors;
-    for (BlockSet::iterator it = blocks.begin(); it != blocks.end(); ++it) {
-        for (const RenderBlock* block = (*it); block; block = block->containingBlock()) {
-            ancestors.add(block);
-            // The first ancestor that has all of the blocks as children wins.
-            if (ancestors.count(block) == blocks.size())
-                return block;
-        }
-    }
-    ASSERT_NOT_REACHED();
-    return 0;
-}
-
 float FastTextAutosizer::clusterMultiplier(Cluster* cluster)
 {
     if (cluster->m_multiplier)
@@ -785,14 +768,7 @@ float FastTextAutosizer::superclusterMultiplier(Cluster* cluster)
         const BlockSet* roots = supercluster->m_roots;
         const RenderBlock* widthProvider;
 
-        if (cluster->m_root->isTableCell()) {
-            widthProvider = clusterWidthProvider(cluster->m_root);
-        } else {
-            BlockSet widthProviders;
-            for (BlockSet::iterator it = roots->begin(); it != roots->end(); ++it)
-                widthProviders.add(clusterWidthProvider(*it));
-            widthProvider = deepestCommonAncestor(widthProviders);
-        }
+        widthProvider = maxClusterWidthProvider(cluster->m_supercluster, cluster->m_root);
 
         supercluster->m_multiplier = anyClusterHasEnoughTextToAutosize(roots, widthProvider)
             ? multiplierFromBlock(widthProvider) : 1.0f;
@@ -809,6 +785,25 @@ const RenderBlock* FastTextAutosizer::clusterWidthProvider(const RenderBlock* ro
     return deepestBlockContainingAllText(root);
 }
 
+
+const RenderBlock* FastTextAutosizer::maxClusterWidthProvider(const Supercluster* supercluster, const RenderBlock* currentRoot)
+{
+    float maxWidth = 0;
+    const RenderBlock* result = 0;
+    const BlockSet* roots = supercluster->m_roots;
+    for (BlockSet::iterator it = roots->begin(); it != roots->end(); ++it) {
+        const RenderBlock* widthProvider = clusterWidthProvider(*it);
+        if (widthProvider != currentRoot && widthProvider->needsLayout())
+            continue;
+        float width = widthFromBlock(widthProvider);
+        if (width > maxWidth) {
+            maxWidth = width;
+            result = widthProvider;
+        }
+    }
+    return result;
+}
+
 float FastTextAutosizer::widthFromBlock(const RenderBlock* block)
 {
     if (block->isTable()) {