Debugger: Initialize QmlV8ObjectData::id

Change-Id: I73ce601e4d74ef662f7789080ed1579802a668f7
Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com>

src/plugins/debugger/qml/qmlengine.cpp

@@ -109,7 +109,7 @@ enum StepAction
 
 struct QmlV8ObjectData
 {
-    int handle;
+    int handle = -1;
     QByteArray name;
     QByteArray type;
     QVariant value;