Function get_stack

test/fixtures/wpt/resources/testharness.js:4801–4837

()

    AssertionError.prototype = Object.create(Error.prototype);

    const get_stack = function() {
        var stack = new Error().stack;

        // 'Error.stack' is not supported in all browsers/versions
        if (!stack) {
            return "(Stack trace unavailable)";
        }

        var lines = stack.split("\n");

        // Create a pattern to match stack frames originating within testharness.js.  These include the
        // script URL, followed by the line/col (e.g., '/resources/testharness.js:120:21').
        // Escape the URL per http://stackoverflow.com/questions/3561493/is-there-a-regexp-escape-function-in-javascript
        // in case it contains RegExp characters.
        var script_url = get_script_url();
        var re_text = script_url ? script_url.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') : "\\btestharness.js";
        var re = new RegExp(re_text + ":\\d+:\\d+");

        // Some browsers include a preamble that specifies the type of the error object.  Skip this by
        // advancing until we find the first stack frame originating from testharness.js.
        var i = 0;
        while (!re.test(lines[i]) && i < lines.length) {
            i++;
        }

        // Then skip the top frames originating from testharness.js to begin the stack at the test code.
        while (re.test(lines[i]) && i < lines.length) {
            i++;
        }

        // Paranoid check that we didn't skip all frames.  If so, return the original stack unmodified.
        if (i >= lines.length) {
            return stack;
        }

        return lines.slice(i).join("\n");
    };

    function OptionalFeatureUnsupportedError(message)
    {