QmlDesigner: Improve speed of undo

Undo works strickly on the text editor and we wait 600ms
until we propagte changes from text editor to the model, to not
interrupt typing. In this case we should force the update immediately.

Task-number: QDS-9440
Change-Id: I5c854e7b4c6936e02c57d4cc7433a6e0ede50af4
(cherry picked from commit d26e35b221)
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/components/integration/designdocument.cpp

@@ -700,16 +700,20 @@ ModelNode DesignDocument::rootModelNode() const
 
 void DesignDocument::undo()
 {
-    if (rewriterView() && !rewriterView()->modificationGroupActive())
+    if (rewriterView() && !rewriterView()->modificationGroupActive()) {
         plainTextEdit()->undo();
+        rewriterView()->forceAmend();
+    }
 
     viewManager().resetPropertyEditorView();
 }
 
 void DesignDocument::redo()
 {
-    if (rewriterView() && !rewriterView()->modificationGroupActive())
+    if (rewriterView() && !rewriterView()->modificationGroupActive()) {
         plainTextEdit()->redo();
+        rewriterView()->forceAmend();
+    }
 
     viewManager().resetPropertyEditorView();
 }

src/plugins/qmldesigner/designercore/include/rewriterview.h

@@ -170,6 +170,8 @@ public:
     bool possibleImportsEnabled() const;
     void setPossibleImportsEnabled(bool b);
 
+    void forceAmend();
+
 signals:
     void modelInterfaceProjectUpdated();
 

src/plugins/qmldesigner/designercore/model/rewriterview.cpp

@@ -703,6 +703,12 @@ void RewriterView::setPossibleImportsEnabled(bool b)
     m_possibleImportsEnabled = b;
 }
 
+void RewriterView::forceAmend()
+{
+    m_amendTimer.stop();
+    amendQmlText();
+}
+
 Internal::ModelNodePositionStorage *RewriterView::positionStorage() const
 {
     return m_positionStorage.data();