function _findMatchingRulesInStyleBlocks(htmlDocument, selector, resultSelectors) {
        // HTMLUtils requires a real CodeMirror instance; make sure we can give it the right Editor
        var htmlEditor = EditorManager.getCurrentFullEditor();
        if (htmlEditor.document !== htmlDocument) {
            console.error("Cannot search for <style> blocks in HTML file other than current editor");
            return;
        }

        // Find all <style> blocks in the HTML file
        var styleBlocks = HTMLUtils.findStyleBlocks(htmlEditor);

        styleBlocks.forEach(function (styleBlockInfo) {
            // Search this one <style> block's content, appending results to 'resultSelectors'
            var oneStyleBlockMatches = _findAllMatchingSelectorsInText(styleBlockInfo.text, selector);
            _addSelectorsToResults(resultSelectors, oneStyleBlockMatches, htmlDocument, styleBlockInfo.start.line);
        });
    }
Finds matching selectors in the <style> block of a single HTML file; adds them to 'resultSelectors'