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/HTMLEmbedElement.cpp

@@ -9,7 +9,7 @@
 #include "mozilla/dom/HTMLEmbedElementBinding.h"
 #include "mozilla/dom/ElementInlines.h"
 
-#include "nsIDocument.h"
+#include "mozilla/dom/Document.h"
 #include "nsIPluginDocument.h"
 #include "nsThreadUtils.h"
 #include "nsIScriptError.h"
@@ -73,8 +73,7 @@ void HTMLEmbedElement::AsyncEventRunning(AsyncEventDispatcher* aEvent) {
   nsImageLoadingContent::AsyncEventRunning(aEvent);
 }
 
-nsresult HTMLEmbedElement::BindToTree(nsIDocument* aDocument,
-                                      nsIContent* aParent,
+nsresult HTMLEmbedElement::BindToTree(Document* aDocument, nsIContent* aParent,
                                       nsIContent* aBindingParent) {
   nsresult rv =
       nsGenericHTMLElement::BindToTree(aDocument, aParent, aBindingParent);
@@ -99,7 +98,7 @@ nsresult HTMLEmbedElement::BindToTree(nsIDocument* aDocument,
 
 void HTMLEmbedElement::UnbindFromTree(bool aDeep, bool aNullParent) {
 #ifdef XP_MACOSX
-  // When a page is reloaded (when an nsIDocument's content is removed), the
+  // When a page is reloaded (when an Document's content is removed), the
   // focused element isn't necessarily sent an eBlur event. See
   // nsFocusManager::ContentRemoved(). This means that a widget may think it
   // still contains a focused plugin when it doesn't -- which in turn can