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.

Change-Id: I5c854e7b4c6936e02c57d4cc7433a6e0ede50af4
Reviewed-by: Burak Hancerli <burak.hancerli@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Thomas Hartmann <thomas.hartmann@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();