Get source code from given URL if in the same domain.

@param url <String> JS source URL
@return <Array> Array of source code lines
function(url) {
	        // TODO reuse source from script tags?
	        if (!(url in this.sourceCache)) {
	            this.sourceCache[url] = this.ajax(url).split('\n');
	        }
	        return this.sourceCache[url];
	    }