remove the old icon when an empty source is set

BUG:339793

reviewer by:Bhushan Shah <bhush94@gmail.com>

Change-Id: I02910e7ec9397c5bb6ca4e5c0ed3793d19aa14e5

src/declarativeimports/core/iconitem.cpp

@@ -95,6 +95,7 @@ void IconItem::setSource(const QVariant &source)
         if (source.toString().isEmpty()) {
             delete m_svgIcon;
             m_svgIcon = 0;
+            m_icon = QIcon();
             m_loadPixmapTimer.start();
             emit validChanged();
             return;