Add back and deprecate atom.showSaveDialogSync

src/atom-environment.js

@@ -1080,6 +1080,13 @@ class AtomEnvironment {
     return this.deserialize(state)
   }
 
+  showSaveDialogSync (options = {}) {
+    deprecate(`atom.showSaveDialogSync is deprecated and will be removed soon.
+Please, implement ::saveAs and ::getSaveDialogOptions instead for pane items
+or use Pane::saveItemAs for programmatic saving.`)
+    return this.applicationDelegate.showSaveDialog(options)
+  }
+
   async saveState (options, storageKey) {
     if (this.enablePersistence && this.project) {
       const state = this.serialize(options)