QmlJSObserver: Fix crash when adding an element to some .qml files

Make sure that the 'artifical' URL of the item created actually is
absolute (starts with a file:///). Otherwise an Assert will be hit
when the imports include e.g. a .js file, and the Engine tries to
load it.

Task-number: QTCREATORBUG-2644
Reviewed-by: Olivier Goffart

src/libs/qmljs/qmljsdelta.cpp

@@ -363,7 +363,8 @@ void Delta::insert(UiObjectMember *member, UiObjectMember *parentMember, const Q
             importList << doc->source().mid(importBegin, importEnd - importBegin);
         }
 
-        QString filename = doc->fileName() + QLatin1Char('_') + QString::number(doc->editorRevision())
+        // encode editorRevision, lineNumber in URL. See ClientProxy::buildDebugIdHashRecursive
+        QString filename = QLatin1String("file://") + doc->fileName() + QLatin1Char('_') + QString::number(doc->editorRevision())
                          + QLatin1Char(':') + QString::number(uiObjectDef->firstSourceLocation().startLine-importList.count());
         foreach(DebugId debugId, debugReferences) {
             if (debugId != -1) {