QmlDesigner: Polish the formeditor split toolbuttons a bit

This gives them a similar look of other toolbuttons
in Qt Creator.

Change-Id: Ib3163ff6c1eab2bd26e46d1136de5fa474dea66d
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/switchsplittabwidget.cpp

@@ -81,7 +81,7 @@ SwitchSplitTabWidget::SwitchSplitTabWidget(QWidget *parent)
     QToolButton *horizontalButton = new QToolButton;
     horizontalButton->setObjectName("centralTabBar");
     horizontalButton->setIcon(Utils::Icon({{QLatin1String(":/qmldesigner/images/spliteditorvertically.png"),
-                                            Utils::Theme::TextColorNormal}}, Utils::Icon::Tint).icon());
+                                            Utils::Theme::IconsBaseColor}}).icon());
     horizontalButton->setIconSize(QSize(8, 16));
     connect(horizontalButton, &QToolButton::clicked, [this] () {
         m_splitter->setOrientation(Qt::Vertical);
@@ -91,7 +91,7 @@ SwitchSplitTabWidget::SwitchSplitTabWidget(QWidget *parent)
     QToolButton *verticalButton = new QToolButton;
     verticalButton->setObjectName("centralTabBar");
     verticalButton->setIcon(Utils::Icon({{QLatin1String(":/qmldesigner/images/spliteditorhorizontally.png"),
-                                          Utils::Theme::TextColorNormal}}, Utils::Icon::Tint).icon());
+                                          Utils::Theme::IconsBaseColor}}).icon());
     verticalButton->setIconSize(QSize(8, 16));
     connect(verticalButton, &QToolButton::clicked, [this] () {
         m_splitter->setOrientation(Qt::Horizontal);