Bug 1517241 - Rename nsIDocument to mozilla::dom::Document. r=smaug

Summary: Really sorry for the size of the patch. It's mostly automatic
s/nsIDocument/Document/ but I had to fix up in a bunch of places manually to
add the right namespacing and such.

Overall it's not a very interesting patch I think.

nsDocument.cpp turns into Document.cpp, nsIDocument.h into Document.h and
nsIDocumentInlines.h into DocumentInlines.h.

I also changed a bunch of nsCOMPtr usage to RefPtr, but not all of it.

While fixing up some of the bits I also removed some unneeded OwnerDoc() null
checks and such, but I didn't do anything riskier than that.

dom/html/HTMLBodyElement.cpp

@@ -14,8 +14,8 @@
 #include "nsStyleConsts.h"
 #include "nsPresContext.h"
 #include "nsIPresShell.h"
-#include "nsIDocument.h"
-#include "nsIDocumentInlines.h"
+#include "mozilla/dom/Document.h"
+#include "DocumentInlines.h"
 #include "nsHTMLStyleSheet.h"
 #include "nsMappedAttributes.h"
 #include "nsIDocShell.h"
@@ -284,8 +284,7 @@ bool HTMLBodyElement::IsEventAttributeNameInternal(nsAtom* aName) {
       aName, EventNameType_HTML | EventNameType_HTMLBodyOrFramesetOnly);
 }
 
-nsresult HTMLBodyElement::BindToTree(nsIDocument* aDocument,
-                                     nsIContent* aParent,
+nsresult HTMLBodyElement::BindToTree(Document* aDocument, nsIContent* aParent,
                                      nsIContent* aBindingParent) {
   nsresult rv =
       nsGenericHTMLElement::BindToTree(aDocument, aParent, aBindingParent);