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

Source/core/editing/ReplaceNodeWithSpanCommand.cpp

Index: Source/core/editing/ReplaceNodeWithSpanCommand.cpp
diff --git a/Source/core/editing/ReplaceNodeWithSpanCommand.cpp b/Source/core/editing/ReplaceNodeWithSpanCommand.cpp
index e09b6a13c37d7c1045c1edf45b986fa968df2566..64f0256b72360123bb7f2f988f1a2f7cc7a16e68 100644
--- a/Source/core/editing/ReplaceNodeWithSpanCommand.cpp
+++ b/Source/core/editing/ReplaceNodeWithSpanCommand.cpp
@@ -42,7 +42,7 @@ namespace WebCore {
 using namespace HTMLNames;
 
 ReplaceNodeWithSpanCommand::ReplaceNodeWithSpanCommand(PassRefPtr<HTMLElement> element)
-    : SimpleEditCommand(element->document())
+    : SimpleEditCommand(&element->document())
     , m_elementToReplace(element)
 {
     ASSERT(m_elementToReplace);
@@ -70,7 +70,7 @@ void ReplaceNodeWithSpanCommand::doApply()
     if (!m_elementToReplace->inDocument())
         return;
     if (!m_spanElement)
-        m_spanElement = createHTMLElement(m_elementToReplace->document(), spanTag);
+        m_spanElement = createHTMLElement(&m_elementToReplace->document(), spanTag);
     swapInNodePreservingAttributesAndChildren(m_spanElement.get(), m_elementToReplace.get());
 }