Bug 1625809 - Remove nsFileControlFrame::AttributeChanged. r=smaug

Syncing tabindex in that attribute callback was wrong since bug 505355.

Differential Revision: https://phabricator.services.mozilla.com/D68740

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

layout/forms/nsFileControlFrame.cpp

@@ -232,9 +232,7 @@ static already_AddRefed<Element> MakeAnonButton(Document* aDoc,
 
   // Make sure access key and tab order for the element actually redirect to the
   // file picking button.
-  RefPtr<HTMLButtonElement> buttonElement =
-      HTMLButtonElement::FromNodeOrNull(button);
-
+  auto* buttonElement = HTMLButtonElement::FromNode(button);
   if (!aAccessKey.IsEmpty()) {
     buttonElement->SetAccessKey(aAccessKey, IgnoreErrors());
   }
@@ -545,22 +543,6 @@ void nsFileControlFrame::SyncDisabledState() {
   }
 }
 
-nsresult nsFileControlFrame::AttributeChanged(int32_t aNameSpaceID,
-                                              nsAtom* aAttribute,
-                                              int32_t aModType) {
-  if (aNameSpaceID == kNameSpaceID_None && aAttribute == nsGkAtoms::tabindex) {
-    if (aModType == MutationEvent_Binding::REMOVAL) {
-      mBrowseFilesOrDirs->UnsetAttr(aNameSpaceID, aAttribute, true);
-    } else {
-      nsAutoString value;
-      mContent->AsElement()->GetAttr(aNameSpaceID, aAttribute, value);
-      mBrowseFilesOrDirs->SetAttr(aNameSpaceID, aAttribute, value, true);
-    }
-  }
-
-  return nsBlockFrame::AttributeChanged(aNameSpaceID, aAttribute, aModType);
-}
-
 void nsFileControlFrame::ContentStatesChanged(EventStates aStates) {
   if (aStates.HasState(NS_EVENT_STATE_DISABLED)) {
     nsContentUtils::AddScriptRunner(new SyncDisabledStateEvent(this));

layout/forms/nsFileControlFrame.h

@@ -25,6 +25,8 @@ class DataTransfer;
 class nsFileControlFrame final : public nsBlockFrame,
                                  public nsIFormControlFrame,
                                  public nsIAnonymousContentCreator {
+  using Element = mozilla::dom::Element;
+
  public:
   NS_DECL_QUERYFRAME
   NS_DECL_FRAMEARENA_HELPERS(nsFileControlFrame)
@@ -57,8 +59,6 @@ class nsFileControlFrame final : public nsBlockFrame,
   virtual nsresult GetFrameName(nsAString& aResult) const override;
 #endif
 
-  nsresult AttributeChanged(int32_t aNameSpaceID, nsAtom* aAttribute,
-                            int32_t aModType) override;
   virtual void ContentStatesChanged(mozilla::EventStates aStates) override;
 
   // nsIAnonymousContentCreator