WMS 1.3.0 Capabilities parser with a capabilities document including sld:GetLegendGraphic element fails

[josegar74]

A WMS 1.3.0 service that has a Capability > Request like:

<sld:GetLegendGraphic>
    <Format>image/png</Format>
    <Format>image/gif</Format>
    <Format>image/jpeg</Format>
    <DCPType>
        <HTTP>
            <Get>
                <OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink"
 xlink:href="http://server/wms/railway?"/>
            </Get>
            <Post>
                <OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink"
 xlink:href="http://server/wms/railway?"/>
            </Post>
        </HTTP>
    </DCPType>
</sld:GetLegendGraphic>

causes the WMS capabilities parser to fail.

I think is related to the WMS v1.3 parser extending v1 instead of v1.1.:

https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Format/WMSCapabilities/v1_3.js#L28

The problem seem that the delegation of the following code fails:

https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Format/WMSCapabilities/v1_3.js#L134-L136

as this.readers.wms.GetLegendGraphic is not defined in v1 parser, only in v1.1 parser.

Code snippet used to parse the WMS capabilities response:

format = new OpenLayers.Format.WMSCapabilities({
      namespaces: {"sld": "http://www.opengis.net/sld", 
"wms": "http://www.opengis.net/wms", 
"xlink": "http://www.w3.org/1999/xlink", 
"xsi": "http://www.w3.org/2001/XMLSchema-instance"}
    });

    OpenLayers.Request.GET({
        url: "http://server/wms/railway?",
        params: {
            SERVICE: "WMS",
            VERSION: "1.3.0",
            REQUEST: "GetCapabilities"
        },
        success: function(request) {
            var doc = request.responseXML;
            if (!doc || !doc.documentElement) {
                doc = request.responseText;
            }
            var capabilities = format.read(doc);

           // Additional code
        },
        failure: function() {
            alert("Trouble getting capabilities doc");
            OpenLayers.Console.error.apply(OpenLayers.Console, arguments);
        }
    });