Fix some problems reported by clang static analyzer

Source/core/rendering/CompositedLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1285 matching lines @@
 
     if (needsSquashingLayers) {
         ASSERT(compositor()->layerSquashingEnabled());
 
         if (!m_squashingLayer) {
             ASSERT(!m_squashingContainmentLayer);
 
             m_squashingLayer = createGraphicsLayer(CompositingReasonOverlap);
             m_squashingLayer->setDrawsContent(true);
             m_squashingLayer->setNeedsDisplay();
-            layersChanged = true;
 
             // FIXME: containment layer needs a new CompositingReason, CompositingReasonOverlap is not appropriate.
             m_squashingContainmentLayer = createGraphicsLayer(CompositingReasonOverlap);
             // FIXME: reflections should force transform-style to be flat in the style: https://bugs.webkit.org/show_bug.cgi?id=106959
             bool preserves3D = renderer()->style()->transformStyle3D() == TransformStyle3DPreserve3D && !renderer()->hasReflection();
             m_squashingContainmentLayer->setPreserves3D(preserves3D);
             layersChanged = true;
         }
 
         ASSERT(m_squashingLayer && m_squashingContainmentLayer);
     } else {
         if (m_squashingLayer) {
             m_squashingLayer->removeFromParent();
             m_squashingLayer = nullptr;
-            layersChanged = true;
             // FIXME: do we need to invalidate something here?
 
             ASSERT(m_squashingContainmentLayer);
             m_squashingContainmentLayer->removeFromParent();
             m_squashingContainmentLayer = nullptr;
             layersChanged = true;
         }
 
         ASSERT(!m_squashingLayer && !m_squashingContainmentLayer);
     }
@@ skipping 870 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore