QmlJS: Initialize error state in PrototypeIterator.

Change-Id: I231b847607d0558080d0dc0b6392bae5b833d65a
Reviewed-on: http://codereview.qt.nokia.com/107
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Leandro T. C. Melo <leandro.melo@nokia.com>

src/libs/qmljs/qmljsinterpreter.cpp

@@ -1743,6 +1743,7 @@ PrototypeIterator::PrototypeIterator(const ObjectValue *start, const Context *co
     : m_current(0)
     , m_next(start)
     , m_context(context)
+    , m_error(NoError)
 {
     if (start)
         m_prototypes.reserve(10);