QmlObserver: Remove breadcrumb widget in observer mode

I wasn't able to get it working on Mac OS X: Putting it on top
of the QGraphicsView doesn't work because Cocoa doesn't allow a
widget to be on top of OpenGL viewport. Embedding it as a
QGraphicsProxyWidget produces lots of Cocoa warnings (raster engine related).

Anyhow, the same widget shows up in the Debugger/Observer tab of
Qt Creator.

Reviewed-by: Lasse Holmstedt

share/qtcreator/qml/qmlobserver/qmlruntime.h

@@ -53,8 +53,6 @@ namespace QmlJSDebugger {
     class QDeclarativeViewObserver;
 }
 
-class CrumblePath;
-
 QT_BEGIN_NAMESPACE
 
 class QDeclarativeView;
@@ -215,7 +213,6 @@ private:
     bool useQmlFileBrowser;
 
     QWidget *m_centralWidget;
-    CrumblePath *m_crumblePathWidget;
 
     QTranslator *translator;
     void loadTranslationFile(const QString& directory);