Use withStackSave in emscripten_async_wget. NFC (#24918)

Author: sbc100

src/lib/libwget.js

@@ -18,7 +18,7 @@ var LibraryWget = {
 
   emscripten_async_wget__deps: [
     '$PATH_FS', '$callUserCallback', '$Browser',
-    '$stackRestore', '$stringToUTF8OnStack',
+    '$withStackSave', '$stringToUTF8OnStack',
     '$FS_mkdirTree',
     '$FS_createPreloadedFile',
     '$FS_unlink',
@@ -33,11 +33,7 @@ var LibraryWget = {
     function doCallback(callback) {
       if (callback) {
         {{{ runtimeKeepalivePop() }}}
-        callUserCallback(() => {
-          var sp = stackSave();
-          {{{ makeDynCall('vp', 'callback') }}}(stringToUTF8OnStack(_file));
-          stackRestore(sp);
-        });
+        callUserCallback(() => withStackSave(() => {{{ makeDynCall('vp', 'callback') }}}(stringToUTF8OnStack(_file))));
       }
     }
     var destinationDirectory = PATH.dirname(_file);

test/code_size/test_codesize_hello_dylink_all.json

@@ -1,7 +1,7 @@
 {
-  "a.out.js": 246873,
+  "a.out.js": 246862,
   "a.out.nodebug.wasm": 597826,
-  "total": 844699,
+  "total": 844688,
   "sent": [
     "IMG_Init",
     "IMG_Load",