use terser and clean-css directly

create a sourcemap as well by default

node_modules/symbol-tree/package.json

@@ -1,8 +1,8 @@
 {
   "_from": "symbol-tree@^3.2.2",
-  "_id": "symbol-tree@3.2.2",
+  "_id": "symbol-tree@3.2.4",
   "_inBundle": false,
-  "_integrity": "sha1-rifbOPZgp64uHDt9G8KQgZuFGeY=",
+  "_integrity": "sha512-9QNk5KwDF+Bvz+PyObkmSYjI5ksVUYtjW7AU22r2NKcfLJcXp96hkDWU3+XndOsUb+AQ9QhfzfCT2O+CNWT5Tw==",
   "_location": "/symbol-tree",
   "_phantomChildren": {},
   "_requested": {
@@ -18,8 +18,8 @@
   "_requiredBy": [
     "/jsdom"
   ],
-  "_resolved": "https://registry.npmjs.org/symbol-tree/-/symbol-tree-3.2.2.tgz",
-  "_shasum": "ae27db38f660a7ae2e1c3b7d1bc290819b8519e6",
+  "_resolved": "https://registry.npmjs.org/symbol-tree/-/symbol-tree-3.2.4.tgz",
+  "_shasum": "430637d248ba77e078883951fb9aa0eed7c63fa2",
   "_spec": "symbol-tree@^3.2.2",
   "_where": "F:\\projects\\p\\minifyfromhtml\\node_modules\\jsdom",
   "author": {
@@ -33,17 +33,16 @@
   "deprecated": false,
   "description": "Turn any collection of objects into its own efficient tree or linked list using Symbol",
   "devDependencies": {
-    "babel-eslint": "^7.1.1",
-    "coveralls": "^2.11.15",
-    "eslint": "^3.12.0",
+    "babel-eslint": "^10.0.1",
+    "coveralls": "^3.0.0",
+    "eslint": "^5.16.0",
     "eslint-plugin-import": "^2.2.0",
     "istanbul": "^0.4.5",
-    "jsdoc-to-markdown": "^3.0.0",
+    "jsdoc-to-markdown": "^5.0.0",
     "tape": "^4.0.0"
   },
   "files": [
-    "lib",
-    "api.md"
+    "lib"
   ],
   "homepage": "https://github.com/jsdom/js-symbol-tree#symbol-tree",
   "keywords": [
@@ -72,5 +71,5 @@
     "predocumentation": "cp readme-header.md README.md",
     "test": "istanbul cover test/SymbolTree.js"
   },
-  "version": "3.2.2"
+  "version": "3.2.4"
 }