--- a/editor/composer/nsComposerCommandsUpdater.cpp
+++ b/editor/composer/nsComposerCommandsUpdater.cpp
@@ -1,15 +1,16 @@
 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/mozalloc.h"           // for operator new
+#include "mozilla/dom/Selection.h"
 #include "nsAString.h"
 #include "nsComponentManagerUtils.h"    // for do_CreateInstance
 #include "nsComposerCommandsUpdater.h"
 #include "nsDebug.h"                    // for NS_ENSURE_TRUE, etc
 #include "nsError.h"                    // for NS_OK, NS_ERROR_FAILURE, etc
 #include "nsICommandManager.h"          // for nsICommandManager
 #include "nsID.h"                       // for NS_GET_IID, etc
 #include "nsIDOMWindow.h"               // for nsIDOMWindow
@@ -336,19 +337,17 @@ nsComposerCommandsUpdater::SelectionIsCo
   nsCOMPtr<nsPIDOMWindowOuter> domWindow = do_QueryReferent(mDOMWindow);
   NS_ENSURE_TRUE(domWindow, true);
 
   nsCOMPtr<nsISelection> domSelection = domWindow->GetSelection();
   if (NS_WARN_IF(!domSelection)) {
     return false;
   }
 
-  bool selectionCollapsed = false;
-  domSelection->GetIsCollapsed(&selectionCollapsed);
-  return selectionCollapsed;
+  return domSelection->AsSelection()->IsCollapsed();
 }
 
 already_AddRefed<nsPICommandUpdater>
 nsComposerCommandsUpdater::GetCommandUpdater()
 {
   nsCOMPtr<nsIDocShell> docShell = do_QueryReferent(mDocShell);
   NS_ENSURE_TRUE(docShell, nullptr);
   nsCOMPtr<nsICommandManager> manager = docShell->GetCommandManager();

--- a/editor/libeditor/TextEditRules.cpp
+++ b/editor/libeditor/TextEditRules.cpp
@@ -417,20 +417,17 @@ TextEditRules::WillInsertBreak(Selection
     if (didTruncate) {
       *aCancel = true;
       return NS_OK;
     }
 
     *aCancel = false;
 
     // if the selection isn't collapsed, delete it.
-    bool bCollapsed;
-    rv = aSelection->GetIsCollapsed(&bCollapsed);
-    NS_ENSURE_SUCCESS(rv, rv);
-    if (!bCollapsed) {
+    if (!aSelection->IsCollapsed()) {
       NS_ENSURE_STATE(mTextEditor);
       rv = mTextEditor->DeleteSelection(nsIEditor::eNone, nsIEditor::eStrip);
       NS_ENSURE_SUCCESS(rv, rv);
     }
 
     WillInsert(*aSelection, aCancel);
     // initialize out param
     // we want to ignore result of WillInsert()
@@ -662,20 +659,17 @@ TextEditRules::WillInsertText(EditAction
   if (IsPasswordEditor()) {
     NS_ENSURE_STATE(mTextEditor);
     nsContentUtils::GetSelectionInTextControl(aSelection,
                                               mTextEditor->GetRoot(),
                                               start, end);
   }
 
   // if the selection isn't collapsed, delete it.
-  bool bCollapsed;
-  rv = aSelection->GetIsCollapsed(&bCollapsed);
-  NS_ENSURE_SUCCESS(rv, rv);
-  if (!bCollapsed) {
+  if (!aSelection->IsCollapsed()) {
     NS_ENSURE_STATE(mTextEditor);
     rv = mTextEditor->DeleteSelection(nsIEditor::eNone, nsIEditor::eStrip);
     NS_ENSURE_SUCCESS(rv, rv);
   }
 
   WillInsert(*aSelection, aCancel);
   // initialize out param
   // we want to ignore result of WillInsert()
@@ -1022,21 +1016,17 @@ TextEditRules::WillDeleteSelection(Selec
     nsCOMPtr<nsIDOMNode> startNode;
     int32_t startOffset;
     nsresult rv =
       EditorBase::GetStartNodeAndOffset(aSelection, getter_AddRefs(startNode),
                                         &startOffset);
     NS_ENSURE_SUCCESS(rv, rv);
     NS_ENSURE_TRUE(startNode, NS_ERROR_FAILURE);
 
-    bool bCollapsed;
-    rv = aSelection->GetIsCollapsed(&bCollapsed);
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    if (!bCollapsed) {
+    if (!aSelection->IsCollapsed()) {
       return NS_OK;
     }
 
     // Test for distance between caret and text that will be deleted
     rv = CheckBidiLevelForDeletion(aSelection, startNode, startOffset,
                                    aCollapsedAction, aCancel);
     NS_ENSURE_SUCCESS(rv, rv);
     if (*aCancel) {

--- a/editor/txtsvc/nsTextServicesDocument.cpp
+++ b/editor/txtsvc/nsTextServicesDocument.cpp
@@ -490,46 +490,41 @@ nsTextServicesDocument::LastSelectedBloc
   *aSelStatus = nsITextServicesDocument::eBlockNotFound;
   *aSelOffset = *aSelLength = -1;
 
   if (!mSelCon || !mIterator) {
     UNLOCK_DOC(this);
     return NS_ERROR_FAILURE;
   }
 
-  nsCOMPtr<nsISelection> domSelection;
-  nsresult rv = mSelCon->GetSelection(nsISelectionController::SELECTION_NORMAL,
-                                      getter_AddRefs(domSelection));
-  if (NS_FAILED(rv)) {
+  RefPtr<Selection> selection =
+    mSelCon->GetDOMSelection(nsISelectionController::SELECTION_NORMAL);
+  if (NS_WARN_IF(!selection)) {
     UNLOCK_DOC(this);
-    return rv;
+    return NS_ERROR_FAILURE;
   }
 
-  RefPtr<Selection> selection = domSelection->AsSelection();
-
-  bool isCollapsed = selection->IsCollapsed();
-
   nsCOMPtr<nsIContentIterator> iter;
   RefPtr<nsRange> range;
   nsCOMPtr<nsIDOMNode>         parent;
 
-  if (isCollapsed) {
+  if (selection->IsCollapsed()) {
     // We have a caret. Check if the caret is in a text node.
     // If it is, make the text node's block the current block.
     // If the caret isn't in a text node, search forwards in
     // the document, till we find a text node.
 
     range = selection->GetRangeAt(0);
 
     if (!range) {
       UNLOCK_DOC(this);
       return NS_ERROR_FAILURE;
     }
 
-    rv = range->GetStartContainer(getter_AddRefs(parent));
+    nsresult rv = range->GetStartContainer(getter_AddRefs(parent));
 
     if (NS_FAILED(rv)) {
       UNLOCK_DOC(this);
       return rv;
     }
 
     if (!parent) {
       UNLOCK_DOC(this);
@@ -600,16 +595,17 @@ nsTextServicesDocument::LastSelectedBloc
              parent, static_cast<int32_t>(offset), false,
              getter_AddRefs(range));
 
       if (NS_FAILED(rv)) {
         UNLOCK_DOC(this);
         return rv;
       }
 
+      bool isCollapsed;
       rv = range->GetCollapsed(&isCollapsed);
 
       if (NS_FAILED(rv)) {
         UNLOCK_DOC(this);
         return rv;
       }
 
       if (isCollapsed) {
@@ -709,17 +705,17 @@ nsTextServicesDocument::LastSelectedBloc
 
     if (!range) {
       UNLOCK_DOC(this);
       return NS_OK; // XXX Really?
     }
 
     // Create an iterator for the range.
 
-    rv = CreateContentIterator(range, getter_AddRefs(iter));
+    nsresult rv = CreateContentIterator(range, getter_AddRefs(iter));
 
     if (NS_FAILED(rv)) {
       UNLOCK_DOC(this);
       return rv;
     }
 
     iter->Last();
 
@@ -775,17 +771,17 @@ nsTextServicesDocument::LastSelectedBloc
 
   range = selection->GetRangeAt(rangeCount - 1);
 
   if (!range) {
     UNLOCK_DOC(this);
     return NS_ERROR_FAILURE;
   }
 
-  rv = range->GetEndContainer(getter_AddRefs(parent));
+  nsresult rv = range->GetEndContainer(getter_AddRefs(parent));
 
   if (NS_FAILED(rv)) {
     UNLOCK_DOC(this);
     return rv;
   }
 
   if (!parent) {
     UNLOCK_DOC(this);
@@ -803,16 +799,17 @@ nsTextServicesDocument::LastSelectedBloc
   rv = CreateDocumentContentRootToNodeOffsetRange(
          parent, static_cast<int32_t>(offset), false, getter_AddRefs(range));
 
   if (NS_FAILED(rv)) {
     UNLOCK_DOC(this);
     return rv;
   }
 
+  bool isCollapsed;
   rv = range->GetCollapsed(&isCollapsed);
 
   if (NS_FAILED(rv)) {
     UNLOCK_DOC(this);
     return rv;
   }
 
   if (isCollapsed) {
@@ -2290,36 +2287,27 @@ nsTextServicesDocument::GetSelection(nsI
   *aSelLength = -1;
 
   NS_ENSURE_TRUE(mDOMDocument && mSelCon, NS_ERROR_FAILURE);
 
   if (mIteratorStatus == nsTextServicesDocument::eIsDone) {
     return NS_OK;
   }
 
-  nsCOMPtr<nsISelection> selection;
-  bool isCollapsed;
-
-  nsresult rv = mSelCon->GetSelection(nsISelectionController::SELECTION_NORMAL,
-                                      getter_AddRefs(selection));
-
-  NS_ENSURE_SUCCESS(rv, rv);
-
+  RefPtr<Selection> selection =
+    mSelCon->GetDOMSelection(nsISelectionController::SELECTION_NORMAL);
   NS_ENSURE_TRUE(selection, NS_ERROR_FAILURE);
 
-  rv = selection->GetIsCollapsed(&isCollapsed);
-
-  NS_ENSURE_SUCCESS(rv, rv);
-
   // XXX: If we expose this method publicly, we need to
   //      add LOCK_DOC/UNLOCK_DOC calls!
 
   // LOCK_DOC(this);
 
-  if (isCollapsed) {
+  nsresult rv;
+  if (selection->IsCollapsed()) {
     rv = GetCollapsedSelection(aSelStatus, aSelOffset, aSelLength);
   } else {
     rv = GetUncollapsedSelection(aSelStatus, aSelOffset, aSelLength);
   }
 
   // UNLOCK_DOC(this);
 
   // XXX The result of GetCollapsedSelection() or GetUncollapsedSelection().