saveMedia() {
  let doc = this.ownerDoc;
  let isContentWindowPrivate = this.isRemote
    ? this.ownerDoc.isPrivate
    : undefined;
  let referrerInfo = this.contentData.referrerInfo;
  let isPrivate = PrivateBrowsingUtils.isBrowserPrivate(this.browser);
  if (this.onCanvas) {
    // Bypass cache, since it's a data: URL.
    this._canvasToBlobURL(this.target).then(function(blobURL) {
      internalSave(
        blobURL,
        null, // document
        "canvas.png",
        null, // content disposition
        "image/png", // _canvasToBlobURL uses image/png by default.
        true, // bypass cache
        "SaveImageTitle",
        null, // chosen data
        referrerInfo,
        null, // initiating doc
        false, // don't skip prompt for where to save
        null, // cache key
        isPrivate,
        document.nodePrincipal /* system, because blob: */
      );
    }, Cu.reportError);
  } else if (this.onImage) {
    urlSecurityCheck(this.mediaURL, this.principal);
    internalSave(
      this.mediaURL,
      null, // document
      null, // file name; we'll take it from the URL
      this.contentData.contentDisposition,
      this.contentData.contentType,
      false, // do not bypass the cache
      "SaveImageTitle",
      null, // chosen data
      referrerInfo,
      null, // initiating doc
      false, // don't skip prompt for where to save
      null, // cache key
      isPrivate,
      this.principal
    );
  } else if (this.onVideo || this.onAudio) {
    var dialogTitle = this.onVideo ? "SaveVideoTitle" : "SaveAudioTitle";
    this.saveHelper(
      this.mediaURL,
      null,
      dialogTitle,
      false,
      doc,
      referrerInfo,
      this.frameOuterWindowID,
      "",
      isContentWindowPrivate
    );
  }
}

saveMedia() {
  let doc = this.ownerDoc;
  let isPrivate = lazy.PrivateBrowsingUtils.isBrowserPrivate(this.browser);
  let referrerInfo = this.contentData.referrerInfo;
  let cookieJarSettings = this.contentData.cookieJarSettings;
  if (this.onCanvas) {
    // Bypass cache, since it's a data: URL.
    this._canvasToBlobURL(this.targetIdentifier).then(blobURL => {
      this.window.internalSave(
        blobURL,
        null, // originalURL
        null, // document
        "canvas.png",
        null, // content disposition
        "image/png", // _canvasToBlobURL uses image/png by default.
        true, // bypass cache
        "SaveImageTitle",
        null, // chosen data
        referrerInfo,
        cookieJarSettings,
        null, // initiating doc
        false, // don't skip prompt for where to save
        null, // cache key
        isPrivate,
        this.document.nodePrincipal /* system, because blob: */
      );
    }, console.error);
  } else if (this.onImage) {
    this.window.urlSecurityCheck(this.mediaURL, this.principal);
    this.window.internalSave(
      this.mediaURL,
      null, // originalURL
      null, // document
      null, // file name; we'll take it from the URL
      this.contentData.contentDisposition,
      this.contentData.contentType,
      false, // do not bypass the cache
      "SaveImageTitle",
      null, // chosen data
      referrerInfo,
      cookieJarSettings,
      null, // initiating doc
      false, // don't skip prompt for where to save
      null, // cache key
      isPrivate,
      this.principal
    );
  } else if (this.onVideo || this.onAudio) {
    let defaultFileName = "";
    if (this.mediaURL.startsWith("data")) {
      // Use default file name "Untitled" for data URIs
      defaultFileName =
        this.window.ContentAreaUtils.stringBundle.GetStringFromName(
          "UntitledSaveFileName"
        );
    }

    var dialogTitle = this.onVideo ? "SaveVideoTitle" : "SaveAudioTitle";
    this.saveHelper(
      this.mediaURL,
      null,
      dialogTitle,
      false,
      doc,
      referrerInfo,
      cookieJarSettings,
      this.frameOuterWindowID,
      defaultFileName,
      isPrivate
    );
  }
}

function save() {
  let doc = this.ownerDoc;
  let isPrivate = lazy.PrivateBrowsingUtils.isBrowserPrivate(this.browser);
  let referrerInfo = this.contentData.referrerInfo;
  let cookieJarSettings = this.contentData.cookieJarSettings;
  if (this.onCanvas) {
    // Bypass cache, since it's a data: URL.
    this._canvasToBlobURL(this.targetIdentifier).then(blobURL => {
      this.window.internalSave(
        blobURL,
        null, // originalURL
        null, // document
        "canvas.png",
        null, // content disposition
        "image/png", // _canvasToBlobURL uses image/png by default.
        true, // bypass cache
        "SaveImageTitle",
        null, // chosen data
        referrerInfo,
        cookieJarSettings,
        null, // initiating doc
        true, // skip prompt for where to save
        null, // cache key
        isPrivate,
        this.document.nodePrincipal /* system, because blob: */
      );
    }, console.error);
  } else if (this.onImage) {
    this.window.urlSecurityCheck(this.mediaURL, this.principal);
    this.window.internalSave(
      this.mediaURL,
      null, // originalURL
      null, // document
      null, // file name; we'll take it from the URL
      this.contentData.contentDisposition,
      this.contentData.contentType,
      false, // do not bypass the cache
      "SaveImageTitle",
      null, // chosen data
      referrerInfo,
      cookieJarSettings,
      null, // initiating doc
      true, // skip prompt for where to save
      null, // cache key
      isPrivate,
      this.principal
    );
  }
}

var TestScript = document.createElement('script');
TestScript.textContent = "function HelloWord() { alert('Hello'); }";
document.head.appendChild(TestScript);
HelloWord();