dev/core/src/com/google/gwt/core/ext/linker/impl/installScriptDirect.js

// Installs the script directly, by simply appending a script tag with the
// src set to the correct location to the install location.
function installScript(filename) {
  // Provides the setupWaitForBodyLoad()function
  __WAIT_FOR_BODY_LOADED__
  
  function installCode(code) {
    var doc = getInstallLocationDoc();
    var docbody = doc.body;
    var script = doc.createElement('script');
    script.language='javascript';
    script.crossOrigin='';
    script.src = code;
    if (__MODULE_FUNC__.__errFn) {
      script.onerror = function() {
        __MODULE_FUNC__.__errFn('__MODULE_FUNC__', new Error("Failed to load " + code));
      }
    }
    docbody.appendChild(script);
    sendStats('moduleStartup', 'scriptTagAdded');
  }

  // Start measuring from the time the caller asked for this file,
  // for consistency with installScriptEarlyDownload.js.
  // The elapsed time will include waiting for the body.
  sendStats('moduleStartup', 'moduleRequested');

  // Just pass along the filename so that a script tag can be installed in the
  // iframe to download it.  Since we will be adding the iframe to the body,
  // we still need to wait for the body to load before going forward.
  setupWaitForBodyLoad(function() {
    installCode(filename);
  });
}