Firefox Issue # Blur - SVG blur applied to SVG image element

HTML

<img class="blur" src="http://css-plus.com/examples/2012/03/gaussian-blur/i/fence.jpg" /><svg>
    <filter id="blur">
        <feGaussianBlur stdDeviation="3" />
    </filter>
</svg>

CSS

.blur {
    height: 300px;
    filter: url(#blur);  
}