message: Added error reporting for sandbox eval on Firefox. Also added resetting the open command tracking variable when playing.
diff: @@ -25,7 +25,7 @@ import ExtCommand from "./ext-command";
  import { xlateArgument } from "./formatCommand";
  import { createPlaybackTree } from "../../playback/playback-tree";
  import { ControlFlowCommandChecks } from "../../models/Command";
  -//import { Sandbox } from "../../../content/sandbox";
  +import parser from "ua-parser-js";
  export const extCommand = new ExtCommand();
  // In order to not break the separation of the execution loop from the state of the playback
  @@ -40,7 +40,7 @@ extCommand.doSetSpeed = (speed) => {
  let baseUrl = "";
  let ignoreBreakpoint = false;
  -//const sandbox = new Sandbox;
  +const browserName = parser(window.navigator.userAgent).browser.name;
  function play(currUrl) {
  baseUrl = currUrl;
  @@ -108,6 +108,9 @@ function executionLoop() {
  }).then(executionLoop);
  });
  } else if (PlaybackState.currentExecutingCommandNode.isControlFlow()) {
  + if (browserName === "Firefox" && !PlaybackState.isOpenCommandUsed) {
  + reportError("Expression evaluation prior to an 'open' command is not supported in Firefox.", false, undefined);
  + }
  return (PlaybackState.isOpenCommandUsed ?
  PlaybackState.currentExecutingCommandNode.execute(extCommand)
  :
  @@ -134,6 +137,7 @@ function executionLoop() {
  }
  function prepareToPlay() {
  + PlaybackState.isOpenCommandUsed = false; // to support deleting an open command and re-running the test to trigger sandbox eval
  return extCommand.init(baseUrl);
  }
  