Bump uglify-js from 3.8.1 to 3.9.0 (#957)

Bumps [uglify-js](https://github.com/mishoo/UglifyJS2) from 3.8.1 to 3.9.0.
- [Release notes](https://github.com/mishoo/UglifyJS2/releases)
- [Commits](https://github.com/mishoo/UglifyJS2/compare/v3.8.1...v3.9.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

package-lock.json

@@ -9413,21 +9413,12 @@
       "dev": true
     },
     "uglify-js": {
-      "version": "3.8.1",
-      "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.8.1.tgz",
-      "integrity": "sha512-W7KxyzeaQmZvUFbGj4+YFshhVrMBGSg2IbcYAjGWGvx8DHvJMclbTDMpffdxFUGPBHjIytk7KJUR/KUXstUGDw==",
+      "version": "3.9.0",
+      "resolved": "https://registry.npmjs.org/uglify-js/-/uglify-js-3.9.0.tgz",
+      "integrity": "sha512-j5wNQBWaql8gr06dOUrfaohHlscboQZ9B8sNsoK5o4sBjm7Ht9dxSbrMXyktQpA16Acaij8AcoozteaPYZON0g==",
       "dev": true,
       "requires": {
-        "commander": "~2.20.3",
-        "source-map": "~0.6.1"
-      },
-      "dependencies": {
-        "source-map": {
-          "version": "0.6.1",
-          "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
-          "integrity": "sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==",
-          "dev": true
-        }
+        "commander": "~2.20.3"
       }
     },
     "unc-path-regex": {