WIP (Introduce WTF::NonNullPtr<T>.)

Source/core/html/HTMLInputElement.cpp

Index: Source/core/html/HTMLInputElement.cpp
diff --git a/Source/core/html/HTMLInputElement.cpp b/Source/core/html/HTMLInputElement.cpp
index 71c55511a59b4653d00684b2cc8594b024615479..970b17d67ac7e4cd87e963c7ce52bdb11825c2fc 100644
--- a/Source/core/html/HTMLInputElement.cpp
+++ b/Source/core/html/HTMLInputElement.cpp
@@ -1525,7 +1525,7 @@ HTMLDataListElement* HTMLInputElement::dataList() const
     if (!m_inputType->shouldRespectListAttribute())
         return 0;
 
-    Element* element = treeScope().getElementById(fastGetAttribute(listAttr));
+    Element* element = treeScope()->getElementById(fastGetAttribute(listAttr));
     if (!element)
         return 0;
     if (!element->hasTagName(datalistTag))
@@ -1808,7 +1808,7 @@ PassOwnPtr<ListAttributeTargetObserver> ListAttributeTargetObserver::create(cons
 }
 
 ListAttributeTargetObserver::ListAttributeTargetObserver(const AtomicString& id, HTMLInputElement* element)
-    : IdTargetObserver(element->treeScope().idTargetObserverRegistry(), id)
+    : IdTargetObserver(element->treeScope()->idTargetObserverRegistry(), id)
     , m_element(element)
 {
 }