Have StyleResolver / StyleResolverState deal with Document references, not pointers

Source/core/css/resolver/StyleResolverState.cpp

Index: Source/core/css/resolver/StyleResolverState.cpp
diff --git a/Source/core/css/resolver/StyleResolverState.cpp b/Source/core/css/resolver/StyleResolverState.cpp
index caefee7f02b5c2591f28120c6f49ba400abefb28..b98a30c462b6c895bc825bfdc876da8421f1ac68 100644
--- a/Source/core/css/resolver/StyleResolverState.cpp
+++ b/Source/core/css/resolver/StyleResolverState.cpp
@@ -29,21 +29,15 @@
 
 namespace WebCore {
 
-StyleResolverState::StyleResolverState(Document* document, Element* element, RenderStyle* parentStyle, RenderRegion* regionForStyling)
-    : m_regionForStyling(0)
+StyleResolverState::StyleResolverState(Document& document, Element* element, RenderStyle* parentStyle, RenderRegion* regionForStyling)
+    : m_elementContext(element ? ElementResolveContext(element) : ElementResolveContext())
+    , m_document(element ? m_elementContext.document() : document)
+    , m_regionForStyling(0)
     , m_applyPropertyToRegularStyle(true)
     , m_applyPropertyToVisitedLinkStyle(false)
     , m_lineHeightValue(0)
     , m_styleMap(*this, m_elementStyleResources)
 {
-    if (element) {
-        m_elementContext = ElementResolveContext(element);
-        m_document = &m_elementContext.document();
-    } else {
-        m_elementContext = ElementResolveContext();
-        m_document = document;
-    }
-
     m_regionForStyling = regionForStyling;
 
     if (m_elementContext.resetStyleInheritance())
@@ -62,7 +56,7 @@ StyleResolverState::StyleResolverState(Document* document, Element* element, Ren
     // FIXME: StyleResolverState is never passed between documents
     // so we should be able to do this initialization at StyleResolverState
     // createion time instead of now, correct?
-    if (Page* page = document->page())
+    if (Page* page = document.page())
         m_elementStyleResources.setDeviceScaleFactor(page->deviceScaleFactor());
 }