Update gulpfile and dependencies

gulpfile.js

@@ -1,5 +1,6 @@
 /*
   Copyright (C) 2014 Yusuke Suzuki <utatane.tea@gmail.com>
+  Copyright (C) 2019-2020 Apple Inc. All rights reserved.
 
   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are met:
@@ -64,20 +65,20 @@ var ESLINT_OPTION = {
     }
 };
 
-gulp.task('test', function () {
+gulp.task('test', gulp.series(function () {
     return gulp.src(TEST)
         .pipe(mocha({
             reporter: 'spec',
             timeout: 100000 // 100s
         }));
-});
+}));
 
-gulp.task('lint', function () {
+gulp.task('lint', gulp.series(function () {
     return gulp.src(LINT)
         .pipe(eslint(ESLINT_OPTION))
         .pipe(eslint.formatEach('stylish', process.stderr))
         .pipe(eslint.failOnError());
-});
+}));
 
-gulp.task('travis', [ 'lint', 'test' ]);
-gulp.task('default', [ 'travis' ]);
+gulp.task('travis', gulp.series([ 'lint', 'test' ]));
+gulp.task('default', gulp.series([ 'travis' ]));

package.json

@@ -32,23 +32,24 @@
     "dependencies": {
         "estraverse": "^5.2.0",
         "esutils": "^2.0.2",
-        "esprima": "^4.0.1",
-        "optionator": "^0.8.1"
+        "esprima": "^4.0.1"
     },
     "optionalDependencies": {
         "source-map": "~0.6.1"
     },
     "devDependencies": {
-        "acorn": "^7.3.1",
+        "acorn": "^8.0.4",
         "bluebird": "^3.4.7",
         "bower-registry-client": "^1.0.0",
         "chai": "^4.2.0",
         "chai-exclude": "^2.0.2",
         "commonjs-everywhere": "^0.9.7",
-        "gulp": "^3.8.10",
-        "gulp-eslint": "^3.0.1",
-        "gulp-mocha": "^3.0.1",
-        "semver": "^5.1.0"
+        "gulp": "^4.0.2",
+        "gulp-eslint": "^6.0.0",
+        "gulp-mocha": "^7.0.2",
+        "minimist": "^1.2.5",
+        "optionator": "^0.9.1",
+        "semver": "^7.3.4"
     },
     "license": "BSD-2-Clause",
     "scripts": {