Simplify 'position' adjustment of top layer elements

Source/core/css/resolver/StyleResolver.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 1525 matching lines @@
         }
 
         // FIXME: We shouldn't be overriding start/-webkit-auto like this. Do it in html.css instead.
         // Table headers with a text-align of -webkit-auto will change the text-align to center.
         if (e && e->hasTagName(thTag) && style->textAlign() == TASTART)
             style->setTextAlign(CENTER);
 
         if (e && e->hasTagName(legendTag))
             style->setDisplay(BLOCK);
 
+        // Per the spec, position 'static' and 'relative' in the top layer compute to 'absolute'.
+        if (e && e->isInTopLayer() && (style->position() == StaticPosition || style->position() == RelativePosition))
+            style->setPosition(AbsolutePosition);
+
         // Absolute/fixed positioned elements, floating elements and the document element need block-like outside display.
         if (style->hasOutOfFlowPosition() || style->isFloating() || (e && e->document()->documentElement() == e))
             style->setDisplay(equivalentBlockDisplay(style->display(), style->isFloating(), !document()->inQuirksMode()));
 
         // FIXME: Don't support this mutation for pseudo styles like first-letter or first-line, since it's not completely
         // clear how that should work.
         if (style->display() == INLINE && style->styleType() == NOPSEUDO && style->writingMode() != parentStyle->writingMode())
             style->setDisplay(INLINE_BLOCK);
 
         // After performing the display mutation, check table rows. We do not honor position:relative or position:sticky on
@@ skipping 14 matching lines @@
         // FIXME: Since we don't support block-flow on flexible boxes yet, disallow setting
         // of block-flow to anything other than TopToBottomWritingMode.
         // https://bugs.webkit.org/show_bug.cgi?id=46418 - Flexible box support.
         if (style->writingMode() != TopToBottomWritingMode && (style->display() == BOX || style->display() == INLINE_BOX))
             style->setWritingMode(TopToBottomWritingMode);
 
         if (isDisplayFlexibleBox(parentStyle->display()) || isDisplayGridBox(parentStyle->display())) {
             style->setFloating(NoFloat);
             style->setDisplay(equivalentBlockDisplay(style->display(), style->isFloating(), !document()->inQuirksMode()));
         }
-
-        // Per the spec, position 'static' and 'relative' in the top layer compute to 'absolute'.
-        if (e && e->isInTopLayer() && (style->position() == StaticPosition || style->position() == RelativePosition)) {
-            style->setPosition(AbsolutePosition);
-            style->setDisplay(BLOCK);
-        }
     }
 
     // Make sure our z-index value is only applied if the object is positioned.
     if (style->position() == StaticPosition && !isDisplayFlexibleBox(parentStyle->display()))
         style->setHasAutoZIndex();
 
     // Auto z-index becomes 0 for the root element and transparent objects. This prevents
     // cases where objects that should be blended as a single unit end up with a non-transparent
     // object wedged in between them. Auto z-index also becomes 0 for objects that specify transforms/masks/reflections.
     if (style->hasAutoZIndex() && ((e && e->document()->documentElement() == e)
@@ skipping 2145 matching lines @@
     info.addMember(m_state, "state");
 
     // FIXME: move this to a place where it would be called only once?
     info.addMember(CSSDefaultStyleSheets::defaultStyle, "defaultStyle");
     info.addMember(CSSDefaultStyleSheets::defaultQuirksStyle, "defaultQuirksStyle");
     info.addMember(CSSDefaultStyleSheets::defaultPrintStyle, "defaultPrintStyle");
     info.addMember(CSSDefaultStyleSheets::defaultViewSourceStyle, "defaultViewSourceStyle");
 }
 
 } // namespace WebCore