Bug 1572685 - part 13: Get rid of `HTMLEditRules::mReturnInEmptyLIKillsList` r=m_kato

`HTMLEditRules::mReturnInEmptyLIKillsList` stores value of
`editor.html.typing.returnInEmptyListItemClosesList` at construction, and it's
set to true unless the pref value is `"false"`.  However, this pref isn't
registered in anywhere (all.js, firefox.js, etc) nor used in comm-central
and BlueGriffon.

Even if I search the pref in the web, I don't see any information so that
this hidden pref must not be used anybody.  Therefore, this patch just removes
this member.

Differential Revision: https://phabricator.services.mozilla.com/D42262

--HG--
extra : moz-landing-system : lando

editor/libeditor/HTMLEditRules.cpp

@@ -187,17 +187,13 @@ class MOZ_RAII AutoSetTemporaryAncestorLimiter final {
  * mozilla::HTMLEditRules
  ********************************************************/
 
-HTMLEditRules::HTMLEditRules()
-    : mHTMLEditor(nullptr),
-      mInitialized(false),
-      mReturnInEmptyLIKillsList(false) {
+HTMLEditRules::HTMLEditRules() : mHTMLEditor(nullptr), mInitialized(false) {
   mIsHTMLEditRules = true;
   InitFields();
 }
 
 void HTMLEditRules::InitFields() {
   mHTMLEditor = nullptr;
-  mReturnInEmptyLIKillsList = true;
 }
 
 nsresult HTMLEditRules::Init(TextEditor* aTextEditor) {
@@ -223,16 +219,6 @@ nsresult HTMLEditRules::Init(TextEditor* aTextEditor) {
     return NS_ERROR_FAILURE;
   }
 
-  // cache any prefs we care about
-  static const char kPrefName[] =
-      "editor.html.typing.returnInEmptyListItemClosesList";
-  nsAutoCString returnInEmptyLIKillsList;
-  Preferences::GetCString(kPrefName, returnInEmptyLIKillsList);
-
-  // only when "false", becomes FALSE.  Otherwise (including empty), TRUE.
-  // XXX Why was this pref designed as a string and not bool?
-  mReturnInEmptyLIKillsList = !returnInEmptyLIKillsList.EqualsLiteral("false");
-
   Element* rootElement = HTMLEditorRef().GetRoot();
   if (NS_WARN_IF(!rootElement && !HTMLEditorRef().GetDocument())) {
     return NS_ERROR_FAILURE;
@@ -8255,7 +8241,7 @@ nsresult HTMLEditRules::ReturnInListItem(Element& aListItem, nsINode& aNode,
   // If we are in an empty item, then we want to pop up out of the list, but
   // only if prefs say it's okay and if the parent isn't the active editing
   // host.
-  if (mReturnInEmptyLIKillsList && host != aListItem.GetParentElement() &&
+  if (host != aListItem.GetParentElement() &&
       IsEmptyBlockElement(aListItem, IgnoreSingleBR::eYes)) {
     nsCOMPtr<nsIContent> leftListNode = aListItem.GetParent();
     // Are we the last list item in the list?

editor/libeditor/HTMLEditRules.h

@@ -1321,7 +1321,6 @@ class HTMLEditRules : public TextEditRules {
  protected:
   HTMLEditor* mHTMLEditor;
   bool mInitialized;
-  bool mReturnInEmptyLIKillsList;
 };
 
 }  // namespace mozilla