Fix crash when using KJSContext::interpreter
Fix crash when using KJSContext::interpreter

It creates a KJSInterpreter giving it a KJSInterpreterHandle *h, it
does not increase the ref in the contrcutor but it decreases it in the
destructor, so after calling interpreter() in a context, the interpreter
is deleted

KDE/kjs,KDE/kjs,KDE/kjs,KDE/kjs,KDE/kjs,KDE/kjs