Timeline: Clear excess row heights when reducing the number of rows

Otherwise, if you increase the number of rows again later you get
surprising results.

Change-Id: I3ec809820716368849415f9dcdb1ec9208844353
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

src/libs/timeline/timelinemodel.cpp

@@ -136,6 +136,8 @@ void TimelineModel::setExpandedRowCount(int rows)
 {
     Q_D(TimelineModel);
     if (d->expandedRowCount != rows) {
+        if (d->rowOffsets.length() > rows)
+            d->rowOffsets.resize(rows);
         d->expandedRowCount = rows;
         emit expandedRowCountChanged();
         if (d->expanded)

tests/auto/timeline/timelinemodel/tst_timelinemodel.cpp

@@ -232,8 +232,12 @@ void tst_TimelineModel::height()
     QCOMPARE(dummy.height(), 2 * DefaultRowHeight);
     dummy.setExpanded(true);
     QCOMPARE(dummy.height(), 3 * DefaultRowHeight);
-    dummy.setExpandedRowHeight(0, 80);
+    dummy.setExpandedRowHeight(1, 80);
     QCOMPARE(dummy.height(), 2 * DefaultRowHeight + 80);
+    dummy.clear();
+    dummy.loadData();
+    dummy.setExpanded(true);
+    QCOMPARE(dummy.rowHeight(1), DefaultRowHeight); // Make sure the row height gets reset.
 }
 
 void tst_TimelineModel::count()