Have Node::document() return a reference instead of a pointer

Source/core/rendering/RenderRegion.cpp

Index: Source/core/rendering/RenderRegion.cpp
diff --git a/Source/core/rendering/RenderRegion.cpp b/Source/core/rendering/RenderRegion.cpp
index 81060903d005f43ed9dcf012120c8050071f597f..7cdd447f58b5b737e2e3856989e3af5c7bc13480 100644
--- a/Source/core/rendering/RenderRegion.cpp
+++ b/Source/core/rendering/RenderRegion.cpp
@@ -209,7 +209,7 @@ void RenderRegion::checkRegionStyle()
     // FIXME: Region styling doesn't work for pseudo elements.
     if (node()) {
         Element* regionElement = toElement(node());
-        customRegionStyle = view()->document()->styleResolver()->checkRegionStyle(regionElement);
+        customRegionStyle = view()->document().styleResolver()->checkRegionStyle(regionElement);
     }
     setHasCustomRegionStyle(customRegionStyle);
     m_flowThread->checkRegionsWithStyling();
@@ -538,13 +538,12 @@ PassRefPtr<RenderStyle> RenderRegion::computeStyleInRegion(const RenderObject* o
 {
     ASSERT(object);
     ASSERT(object->view());
-    ASSERT(object->view()->document());
     ASSERT(!object->isAnonymous());
     ASSERT(object->node() && object->node()->isElementNode());
 
     // FIXME: Region styling fails for pseudo-elements because the renderers don't have a node.
     Element* element = toElement(object->node());
-    RefPtr<RenderStyle> renderObjectRegionStyle = object->view()->document()->styleResolver()->styleForElement(element, 0, DisallowStyleSharing, MatchAllRules, this);
+    RefPtr<RenderStyle> renderObjectRegionStyle = object->view()->document().styleResolver()->styleForElement(element, 0, DisallowStyleSharing, MatchAllRules, this);
 
     return renderObjectRegionStyle.release();
 }