Make cluster creation independent of fingerprinting. Keep track of current

Source/core/rendering/TextAutosizer.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2012 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, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 507 matching lines @@
     //
     // Clusters are chosen using very similar criteria to CSS flow roots, aka
     // block formatting contexts (http://w3.org/TR/css3-box/#flow-root), since
     // flow roots correspond to box containers that behave somewhat
     // independently from their parent (for example they don't overlap floats).
     // The definition of a flow root also conveniently includes most of the
     // ways that a box and its children can have significantly different width
     // from the box's parent (we want to avoid having significantly different
     // width blocks within a cluster, since the narrower blocks would end up
     // larger than would otherwise be necessary).
+    RenderBlock* containingBlock = renderer->containingBlock();
     return renderer->isRenderView()
         || renderer->isFloating()
         || renderer->isOutOfFlowPositioned()
         || renderer->isTableCell()
         || renderer->isTableCaption()
         || renderer->isFlexibleBoxIncludingDeprecated()
         || renderer->hasColumns()
-        || renderer->containingBlock()->isHorizontalWritingMode() != renderer->isHorizontalWritingMode()
+        || (containingBlock && containingBlock->isHorizontalWritingMode() != renderer->isHorizontalWritingMode())
         || renderer->style()->isDisplayReplacedType()
         || renderer->isTextArea()
         || renderer->style()->userModify() != READ_ONLY;
     // FIXME: Tables need special handling to multiply all their columns by
     // the same amount even if they're different widths; so do hasColumns()
     // containers, and probably flexboxes...
 }
 
 bool TextAutosizer::isAutosizingCluster(const RenderBlock* renderer, TextAutosizingClusterInfo& parentClusterInfo)
 {
@@ skipping 250 matching lines @@
         if (i + 1 < clusterInfos.size()) {
             float currentWidth = clusterInfos[i].root->contentLogicalWidth();
             float nextWidth = clusterInfos[i + 1].root->contentLogicalWidth();
             if (currentWidth - nextWidth > maxWidthDifferenceWithinGroup)
                 groups.grow(groups.size() + 1);
         }
     }
 }
 
 } // namespace WebCore