netlog_viewer/netlog_viewer/ui_webui_resources_js_util.js
function queryRequiredElement(selectors, opt_context) {
  var element = (opt_context || document).querySelector(selectors);
  return assertInstanceof(element, HTMLElement,
                          'Missing required element: ' + selectors);
}
function queryRequiredElement(selectors, opt_context) {
  var element = (opt_context || document).querySelector(selectors);
  return assertInstanceof(element, HTMLElement,
                          'Missing required element: ' + selectors);
}
function queryRequiredElement ( selectors , opt_context ) { var element = ( opt_context || document ) . querySelector ( selectors ) ; return assertInstanceof ( element , HTMLElement , 'Missing required element: ' + selectors ) ; }
Query an element that's known to exist by a selector. We use this instead of
just calling querySelector and not checking the result because this lets us
satisfy the JSCompiler type system.
@param {string} selectors CSS selectors to query the element.
@param {(!Document|!DocumentFragment|!Element)=} opt_context An optional
context object for querySelector.
@return {!HTMLElement} the Element.
Query an element that s known to exist by a selector . We use this instead of just calling querySelector and not checking the result because this lets us satisfy the JSCompiler type system .