Fix for clean-css vulnerability

ember-cli/ember-cli-preprocess-registry#50

package.json

@@ -63,6 +63,9 @@
     "ember-cli-htmlbars": "^4.2.2",
     "fastboot-transform": "^0.1.3"
   },
+  "resolutions": {
+    "clean-css": "4.2.1"
+  },
   "keywords": [
     "ember-addon",
     "ember-cli",

yarn.lock

@@ -3627,13 +3627,12 @@ clean-css-promise@^0.1.0:
     clean-css "^3.4.5"
     pinkie-promise "^2.0.0"
 
-clean-css@^3.4.5:
-  version "3.4.28"
-  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-3.4.28.tgz#bf1945e82fc808f55695e6ddeaec01400efd03ff"
-  integrity sha1-vxlF6C/ICPVWlebd6uwBQA79A/8=
+clean-css@4.2.1, clean-css@^3.4.5:
+  version "4.2.1"
+  resolved "https://registry.npmjs.org/clean-css/-/clean-css-4.2.1.tgz#2d411ef76b8569b6d0c84068dabe85b0aa5e5c17"
+  integrity sha512-4ZxI6dy4lrY6FHzfiy1aEOXgu4LIsW2MhwG0VBKdcoGoH/XLFgaHSdLTGr4O8Be6A8r3MOphEiI8Gc1n0ecf3g==
   dependencies:
-    commander "2.8.x"
-    source-map "0.4.x"
+    source-map "~0.6.0"
 
 clean-up-path@^1.0.0:
   version "1.0.0"
@@ -3766,13 +3765,6 @@ [email protected]:
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.12.2.tgz#0f5946c427ed9ec0d91a46bb9def53e54650e555"
   integrity sha512-BFnaq5ZOGcDN7FlrtBT4xxkgIToalIIxwjxLWVJ8bGTpe1LroqMiqQXdA7ygc7CRvaYS+9zfPGFnJqFSayx+AA==
 
-[email protected]:
-  version "2.8.1"
-  resolved "https://registry.yarnpkg.com/commander/-/commander-2.8.1.tgz#06be367febfda0c330aa1e2a072d3dc9762425d4"
-  integrity sha1-Br42f+v9oMMwqh4qBy09yXYkJdQ=
-  dependencies:
-    graceful-readlink ">= 1.0.0"
-
 commander@^2.15.1, commander@^2.20.0, commander@^2.6.0, commander@~2.20.3:
   version "2.20.3"
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.20.3.tgz#fd485e84c03eb4881c20722ba48035e8531aeb33"
@@ -6430,11 +6422,6 @@ graceful-fs@^4.1.11, graceful-fs@^4.1.15, graceful-fs@^4.1.2, graceful-fs@^4.1.3
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.2.3.tgz#4a12ff1b60376ef09862c2093edd908328be8423"
   integrity sha512-a30VEBm4PEdx1dRB7MFK7BejejvCvBronbLjht+sHuGYj8PHs7M/5Z+rt5lw551vZ7yfTCj4Vuyy3mSJytDWRQ==
 
-"graceful-readlink@>= 1.0.0":
-  version "1.0.1"
-  resolved "https://registry.yarnpkg.com/graceful-readlink/-/graceful-readlink-1.0.1.tgz#4cafad76bc62f02fa039b2f94e9a3dd3a391a725"
-  integrity sha1-TK+tdrxi8C+gObL5Tpo906ORpyU=
-
 growly@^1.3.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/growly/-/growly-1.3.0.tgz#f10748cbe76af964b7c96c93c6bcc28af120c081"
@@ -9997,7 +9984,7 @@ source-map-url@^0.4.0:
   resolved "https://registry.yarnpkg.com/source-map-url/-/source-map-url-0.4.0.tgz#3e935d7ddd73631b97659956d55128e87b5084a3"
   integrity sha1-PpNdfd1zYxuXZZlW1VEo6HtQhKM=
 
-source-map@0.4.x, source-map@^0.4.2:
+source-map@^0.4.2:
   version "0.4.4"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.4.4.tgz#eba4f5da9c0dc999de68032d8b4f76173652036b"
   integrity sha1-66T12pwNyZneaAMti092FzZSA2s=
@@ -10009,9 +9996,9 @@ source-map@^0.5.0, source-map@^0.5.6, source-map@^0.5.7:
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc"
   integrity sha1-igOdLRAh0i0eoUyA2OpGi6LvP8w=
 
-source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.1:
+source-map@^0.6.0, source-map@^0.6.1, source-map@~0.6.0, source-map@~0.6.1:
   version "0.6.1"
-  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
+  resolved "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz#74722af32e9614e9c287a8d0bbde48b5e2f1a263"
   integrity sha512-UjgapumWlbMhkBgzT7Ykc5YXUT46F0iKu8SGXq0bcwP5dz/h0Plj6enJqjz1Zbq2l5WaqYnrVbwWOWMyF3F47g==
 
 source-map@~0.1.x: