Bug 1728537 - Part 1: Move SaveState out of nsIFormControl; r=smaug

And make it return void as the return value isn't used at callsites.

Differential Revision: https://phabricator.services.mozilla.com/D124179

dom/html/HTMLSelectElement.cpp

@@ -1249,13 +1249,10 @@ EventStates HTMLSelectElement::IntrinsicState() const {
   return state;
 }
 
-// nsIFormControl
-
-NS_IMETHODIMP
-HTMLSelectElement::SaveState() {
+void HTMLSelectElement::SaveState() {
   PresState* presState = GetPrimaryPresState();
   if (!presState) {
-    return NS_OK;
+    return;
   }
 
   SelectContentData state;
@@ -1283,10 +1280,10 @@ HTMLSelectElement::SaveState() {
     presState->disabled() = HasAttr(kNameSpaceID_None, nsGkAtoms::disabled);
     presState->disabledSet() = true;
   }
-
-  return NS_OK;
 }
 
+// nsIFormControl
+
 bool HTMLSelectElement::RestoreState(PresState* aState) {
   // Get the presentation state object to retrieve our stuff out of.
   const PresContentData& state = aState->contentData();