Remove postcss-extend (#21046)

package.json

@@ -134,7 +134,6 @@
     "node-fetch": "^2.6.7",
     "optimize-css-assets-webpack-plugin": "^5.0.4",
     "postcss-easings": "^2.0.0",
-    "postcss-extend": "^1.0.5",
     "postcss-hexrgba": "^2.0.1",
     "postcss-import": "^12.0.1",
     "postcss-loader": "^3.0.0",

webpack.config.js

@@ -329,7 +329,6 @@ module.exports = (env, argv) => {
                                     require('postcss-import')(),
                                     require("postcss-mixins")(),
                                     require("postcss-simple-vars")(),
-                                    require("postcss-extend")(),
                                     require("postcss-nested")(),
                                     require("postcss-easings")(),
                                     require("postcss-strip-inline-comments")(),

yarn.lock

@@ -9594,13 +9594,6 @@ postcss-env-function@^2.0.2:
     postcss "^7.0.2"
     postcss-values-parser "^2.0.0"
 
-postcss-extend@^1.0.5:
-  version "1.0.5"
-  resolved "https://registry.yarnpkg.com/postcss-extend/-/postcss-extend-1.0.5.tgz#5ea98bf787ba3cacf4df4609743f80a833b1d0e7"
-  integrity sha1-XqmL94e6PKz030YJdD+AqDOx0Oc=
-  dependencies:
-    postcss "^5.0.4"
-
 postcss-focus-visible@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/postcss-focus-visible/-/postcss-focus-visible-4.0.0.tgz#477d107113ade6024b14128317ade2bd1e17046e"
@@ -10166,7 +10159,7 @@ postcss-values-parser@^2.0.0, postcss-values-parser@^2.0.1:
     indexes-of "^1.0.1"
     uniq "^1.0.1"
 
-postcss@^5.0.18, postcss@^5.0.4:
+postcss@^5.0.18:
   version "5.2.18"
   resolved "https://registry.yarnpkg.com/postcss/-/postcss-5.2.18.tgz#badfa1497d46244f6390f58b319830d9107853c5"
   integrity sha512-zrUjRRe1bpXKsX1qAJNJjqZViErVuyEkMTRrwu4ud4sbTtIBRmtaYDrHmcGgmrbsW3MHfmtIf+vJumgQn+PrXg==