Fix some problems reported by clang static analyzer

Source/core/rendering/RenderLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 2055 matching lines @@
         beginTransparencyLayers(context, paintingInfo.rootLayer, paintingInfo.paintDirtyRect, paintingInfo.paintBehavior);
 
     LayerPaintingInfo localPaintingInfo(paintingInfo);
     FilterEffectRendererHelper filterPainter(filterRenderer() && paintsWithFilters());
     if (filterPainter.haveFilterEffect() && !context->paintingDisabled()) {
         RenderLayerFilterInfo* filterInfo = this->filterInfo();
         ASSERT(filterInfo);
         LayoutRect filterRepaintRect = filterInfo->dirtySourceRect();
         filterRepaintRect.move(offsetFromRoot.x(), offsetFromRoot.y());
 
-        if (!rootRelativeBoundsComputed) {
+        if (!rootRelativeBoundsComputed)
             rootRelativeBounds = calculateLayerBounds(paintingInfo.rootLayer, &offsetFromRoot, 0);
-            rootRelativeBoundsComputed = true;
-        }
 
         if (filterPainter.prepareFilterEffect(this, rootRelativeBounds, paintingInfo.paintDirtyRect, filterRepaintRect)) {
             // Now we know for sure, that the source image will be updated, so we can revert our tracking repaint rect back to zero.
             filterInfo->resetDirtySourceRect();
 
             // Rewire the old context to a memory buffer, so that we can capture the contents of the layer.
             // NOTE: We saved the old context in the "transparencyLayerContext" local variable, to be able to start a transparency layer
             // on the original context and avoid duplicating "beginFilterEffect" after each transparency layer call. Also, note that
             // beginTransparencyLayers will only create a single lazy transparency layer, even though it is called twice in this method.
             context = filterPainter.beginFilterEffect(context);
@@ skipping 1994 matching lines @@
     }
 }
 
 void showLayerTree(const WebCore::RenderObject* renderer)
 {
     if (!renderer)
         return;
     showLayerTree(renderer->enclosingLayer());
 }
 #endif