Debugger: Fix removal of expression that ends with whitespace

* Start a debugging session
* Add an evaluated expression "(char*)foo "
* Delete the expression
* Press F10
* It reappears

Change-Id: I5c54ca6ab2f4be6c613880a2747e4aff653d15be
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

src/plugins/debugger/watchwindow.cpp

@@ -1108,7 +1108,7 @@ void WatchTreeView::inputNewExpression()
         "\">documentation</a>."));
     dlg.setHistoryCompleter(QLatin1String("WatchItems"));
     if (dlg.exec() == QDialog::Accepted) {
-        QString exp = dlg.text();
+        const QString exp = dlg.text().trimmed();
         if (!exp.isEmpty())
             watchExpression(exp, exp);
     }