Debugger: Make the console usable in dark themes

This change adds even more stylesheet code to make the background white,
and the editor text black.

Task-number: QTCREATORBUG-16556
Change-Id: I48cf5c825a7600406c289c25ba7c421cd3634a97
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/plugins/debugger/console/consoleview.cpp

@@ -98,7 +98,9 @@ ConsoleView::ConsoleView(ConsoleItemModel *model, QWidget *parent) :
                                 "QTreeView::branch:open:has-children:!has-siblings,"
                                 "QTreeView::branch:open:has-children:has-siblings  {"
                                 "border-image: none;"
-                                "image: none; }"));
+                                "image: none; }"
+                                "QTreeView {"
+                                "background-color: white; }"));
 
     QString baseName = QApplication::style()->objectName();
     if (Utils::HostOsInfo::isAnyUnixHost() && !Utils::HostOsInfo::isMacHost()