The patch used in draw.io to load diagrams that had their outer XML element stripped by saving in Firefox 20

Editor.setGraphXml.js

/**
 * Sets the XML node for the current diagram.
 */
Editor.prototype.setGraphXml = function(node)
{
  var dec = new mxCodec(node.ownerDocument);
	
	if (node.nodeName == 'mxGraphModel')
	{
		this.graph.view.scale = 1;
		this.graph.gridEnabled = node.getAttribute('grid') != '0';
		this.graph.graphHandler.guidesEnabled = node.getAttribute('guides') != '0';
		this.graph.setTooltips(node.getAttribute('tooltips') != '0');
		this.graph.setConnectable(node.getAttribute('connect') != '0');
		this.graph.foldingEnabled = node.getAttribute('fold') != '0';
		this.graph.scrollbars = node.getAttribute('scrollbars') != '0';
		
		if (!this.graph.scrollbars)
		{
			this.graph.container.scrollLeft = 0;
			this.graph.container.scrollTop = 0;
			this.graph.view.translate.x = Number(node.getAttribute('dx') || 0);
			this.graph.view.translate.y = Number(node.getAttribute('dy') || 0);
		}

		this.graph.pageVisible = node.getAttribute('page') == '1';
		this.graph.pageBreaksVisible = this.graph.pageVisible; 
		this.graph.preferPageSize = this.graph.pageBreaksVisible;
		
		// Loads the persistent state settings
		var ps = node.getAttribute('pageScale');
		
		if (ps != null)
		{
			this.graph.pageScale = ps;
		}
		else
		{
			this.graph.pageScale = 1.5;
		}
		
		var pw = node.getAttribute('pageWidth');
		var ph = node.getAttribute('pageHeight');
		
		if (pw != null && ph != null)
		{
			this.graph.pageFormat = new mxRectangle(0, 0, parseFloat(pw), parseFloat(ph));
			this.outline.outline.pageFormat = this.graph.pageFormat;
		}

		// Loads the persistent state settings
		var bg = node.getAttribute('background');
		
		if (bg != null && bg.length > 0)
		{
			this.graph.background = bg;
		}
		
		dec.decode(node, this.graph.getModel());
		this.updateGraphComponents();
	}
	else
	{
		// Workaround for invalid XML output in Firefox 20 due to bug in mxUtils.getXml
		var wrapper = dec.document.createElement('mxGraphModel');
		wrapper.appendChild(node);
		
		dec.decode(wrapper, this.graph.getModel());
		this.updateGraphComponents();
	}
};