Put LayoutAnalyzer back behind disabled-by-default-blink.debug.layout.

Source/core/layout/LayoutBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 363 matching lines @@
             layer->updateDescendantDependentFlags();
             hasVisibleContent = layer->hasVisibleContent();
         }
         if (hasVisibleContent)
             setShouldInvalidateOverflowForPaint(true);
     }
 
     if (isHTMLDialogElement(node()) && isOutOfFlowPositioned())
         positionDialog();
 
-    frameView()->layoutAnalyzer().increment((frameRect() == prevRect) ? LayoutAnalyzer::LayoutBlockRectangleDidNotChange : LayoutAnalyzer::LayoutBlockRectangleChanged);
+    if (LayoutAnalyzer* analyzer = frameView()->layoutAnalyzer())
+        analyzer->increment((frameRect() == prevRect) ? LayoutAnalyzer::LayoutBlockRectangleDidNotChange : LayoutAnalyzer::LayoutBlockRectangleChanged);
 
     clearNeedsLayout();
 }
 
 inline bool LayoutBlockFlow::layoutBlockFlow(bool relayoutChildren, LayoutUnit &pageLogicalHeight, SubtreeLayoutScope& layoutScope)
 {
     LayoutUnit oldLeft = logicalLeft();
     bool logicalWidthChanged = updateLogicalWidthAndColumnWidth();
     relayoutChildren |= logicalWidthChanged;
 
@@ skipping 2759 matching lines @@
     FrameView* frameView = document().view();
     LayoutUnit top = (style()->position() == FixedPosition) ? 0 : frameView->scrollOffset().height();
     int visibleHeight = frameView->visibleContentRect(IncludeScrollbars).height();
     if (size().height() < visibleHeight)
         top += (visibleHeight - size().height()) / 2;
     setY(top);
     dialog->setCentered(top);
 }
 
 } // namespace blink