Bug 1540015 - part 3: Rename Document::GetShell() to Document::GetPresShell() and make it return PresShell* rather than nsIPresShell* r=smaug,emilio

This makes `Document::GetShell()` return `PresShell*` instead of `nsIPresShell`.

Additonally, "shell" is unclear ("docshell" vs. "presshell").  Therefore, this
also renames `Document::GetShell()` to `Document::GetPresShell()`.

Similarly, some other method names of `Document` are also renamed from
`*Shell*` to `*PresShell*`.

Differential Revision: https://phabricator.services.mozilla.com/D25338

dom/base/nsObjectLoadingContent.cpp

@@ -26,7 +26,6 @@
 #include "nsPluginInstanceOwner.h"
 #include "nsJSNPRuntime.h"
 #include "nsINestedURI.h"
-#include "nsIPresShell.h"
 #include "nsScriptSecurityManager.h"
 #include "nsIScriptSecurityManager.h"
 #include "nsIStreamConverterService.h"
@@ -92,6 +91,7 @@
 #include "mozilla/dom/HTMLObjectElement.h"
 #include "mozilla/net/UrlClassifierFeatureFactory.h"
 #include "mozilla/LoadInfo.h"
+#include "mozilla/PresShell.h"
 #include "nsChannelClassifier.h"
 #include "nsFocusManager.h"
 
@@ -2485,9 +2485,9 @@ void nsObjectLoadingContent::NotifyStateChanged(ObjectType aOldType,
   } else if (aOldType != mType) {
     // If our state changed, then we already recreated frames
     // Otherwise, need to do that here
-    nsCOMPtr<nsIPresShell> shell = doc->GetShell();
-    if (shell) {
-      shell->PostRecreateFramesFor(thisEl);
+    RefPtr<PresShell> presShell = doc->GetPresShell();
+    if (presShell) {
+      presShell->PostRecreateFramesFor(thisEl);
     }
   }