Avoid double confirmation when closing sketch

Fixes #8413

handleQuit() already checks for confirmation if the sketch has been modified (when invoked directly).
When invoked indirectly (via handleClose(), as we are closing the last open Editor instance), checkModified() is redundant.

Author: facchinm

app/src/processing/app/Base.java

@@ -926,10 +926,6 @@ public void actionPerformed(ActionEvent actionEvent) {
    * @return true if succeeded in closing, false if canceled.
    */
   public boolean handleClose(Editor editor) {
-    // Check if modified
-    if (!editor.checkModified()) {
-      return false;
-    }
 
     if (editors.size() == 1) {
       handleQuit();
@@ -939,6 +935,10 @@ public boolean handleClose(Editor editor) {
     } else {
       // More than one editor window open,
       // proceed with closing the current window.
+      // Check if modified
+      if (!editor.checkModified()) {
+        return false;
+      }
       editor.setVisible(false);
       editor.dispose();
       editors.remove(editor);