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

Source/core/html/HTMLMeterElement.cpp

Index: Source/core/html/HTMLMeterElement.cpp
diff --git a/Source/core/html/HTMLMeterElement.cpp b/Source/core/html/HTMLMeterElement.cpp
index 0f4a9989f573d007ff371724dad6c8c6f2ed1b10..9f683caf1c4049f6b5079c960392873c8f41748a 100644
--- a/Source/core/html/HTMLMeterElement.cpp
+++ b/Source/core/html/HTMLMeterElement.cpp
@@ -226,11 +226,11 @@ void HTMLMeterElement::didAddUserAgentShadowRoot(ShadowRoot* root)
 {
     ASSERT(!m_value);
 
-    RefPtr<MeterInnerElement> inner = MeterInnerElement::create(document());
+    RefPtr<MeterInnerElement> inner = MeterInnerElement::create(&document());
     root->appendChild(inner);
 
-    RefPtr<MeterBarElement> bar = MeterBarElement::create(document());
-    m_value = MeterValueElement::create(document());
+    RefPtr<MeterBarElement> bar = MeterBarElement::create(&document());
+    m_value = MeterValueElement::create(&document());
     m_value->setWidthPercentage(0);
     m_value->updatePseudo();
     bar->appendChild(m_value);