Fix crash in Form class wizard

Run parents initializePage, not the one from our grandparent.

Task-number: QTCREATORBUG-14620
Change-Id: I1ec2d424c0e6fd6d7dea1050d5d8f6b8f00d27d5
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/designer/cpp/formclasswizarddialog.cpp

@@ -72,7 +72,7 @@ bool FormClassWizardDialog::validateCurrentPage()
 
 void FormClassWizardDialog::initializePage(int id)
 {
-    QWizard::initializePage(id);
+    Core::BaseFileWizard::initializePage(id);
     // Switching from form to class page: store XML template and set a suitable
     // class name in the class page based on the form base class
     if (id == ClassPageId) {