Bump clean-css from 4.1.7 to 4.1.11

Bumps [clean-css](https://github.com/jakubpawlowicz/clean-css) from 4.1.7 to 4.1.11.
- [Release notes](https://github.com/jakubpawlowicz/clean-css/releases)
- [Changelog](https://github.com/jakubpawlowicz/clean-css/blob/master/History.md)
- [Commits](clean-css/clean-css@v4.1.7...v4.1.11)

Signed-off-by: dependabot[bot] <[email protected]>

yarn.lock

@@ -834,6 +834,14 @@ babel-plugin-transform-strict-mode@^6.24.1:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
+babel-polyfill@^6.26.0:
+  version "6.26.0"
+  resolved "https://registry.yarnpkg.com/babel-polyfill/-/babel-polyfill-6.26.0.tgz#379937abc67d7895970adc621f284cd966cf2153"
+  dependencies:
+    babel-runtime "^6.26.0"
+    core-js "^2.5.0"
+    regenerator-runtime "^0.10.5"
+
 [email protected]:
   version "1.5.2"
   resolved "https://registry.yarnpkg.com/babel-preset-env/-/babel-preset-env-1.5.2.tgz#cd4ae90a6e94b709f97374b33e5f8b983556adef"
@@ -928,6 +936,13 @@ [email protected], babel-runtime@^6.18.0, babel-runtime@^6.22.0:
     core-js "^2.4.0"
     regenerator-runtime "^0.10.0"
 
+babel-runtime@^6.26.0:
+  version "6.26.0"
+  resolved "https://registry.yarnpkg.com/babel-runtime/-/babel-runtime-6.26.0.tgz#965c7058668e82b55d7bfe04ff2337bc8b5647fe"
+  dependencies:
+    core-js "^2.4.0"
+    regenerator-runtime "^0.11.0"
+
 babel-template@^6.16.0, babel-template@^6.24.1, babel-template@^6.25.0:
   version "6.25.0"
   resolved "https://registry.yarnpkg.com/babel-template/-/babel-template-6.25.0.tgz#665241166b7c2aa4c619d71e192969552b10c071"
@@ -1309,8 +1324,8 @@ clap@^1.0.9:
     chalk "^1.1.3"
 
 [email protected]:
-  version "4.1.7"
-  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.7.tgz#b9aea4f85679889cf3eae8b40349ec4ebdfdd032"
+  version "4.1.11"
+  resolved "https://registry.yarnpkg.com/clean-css/-/clean-css-4.1.11.tgz#2ecdf145aba38f54740f26cefd0ff3e03e125d6a"
   dependencies:
     source-map "0.5.x"
 
@@ -1522,6 +1537,10 @@ core-js@^2.4.0:
   version "2.4.1"
   resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.4.1.tgz#4de911e667b0eae9124e34254b53aea6fc618d3e"
 
+core-js@^2.5.0:
+  version "2.6.12"
+  resolved "https://registry.yarnpkg.com/core-js/-/core-js-2.6.12.tgz#d9333dfa7b065e347cc5682219d6f690859cc2ec"
+
 core-util-is@~1.0.0:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/core-util-is/-/core-util-is-1.0.2.tgz#b5fd54220aa2bc5ab57aab7140c940754503c1a7"
@@ -5198,10 +5217,14 @@ regenerate@^1.2.1:
   version "1.3.2"
   resolved "https://registry.yarnpkg.com/regenerate/-/regenerate-1.3.2.tgz#d1941c67bad437e1be76433add5b385f95b19260"
 
-regenerator-runtime@^0.10.0:
+regenerator-runtime@^0.10.0, regenerator-runtime@^0.10.5:
   version "0.10.5"
   resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.10.5.tgz#336c3efc1220adcedda2c9fab67b5a7955a33658"
 
+regenerator-runtime@^0.11.0:
+  version "0.11.1"
+  resolved "https://registry.yarnpkg.com/regenerator-runtime/-/regenerator-runtime-0.11.1.tgz#be05ad7f9bf7d22e056f9726cee5017fbf19e2e9"
+
 [email protected]:
   version "0.9.11"
   resolved "https://registry.yarnpkg.com/regenerator-transform/-/regenerator-transform-0.9.11.tgz#3a7d067520cb7b7176769eb5ff868691befe1283"
@@ -5632,10 +5655,14 @@ source-map-support@^0.4.2:
   dependencies:
     source-map "^0.5.6"
 
-[email protected], [email protected], source-map@^0.5.0, source-map@^0.5.3, source-map@^0.5.6, source-map@~0.5.1, source-map@~0.5.3:
+[email protected]:
   version "0.5.6"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.6.tgz#75ce38f52bf0733c5a7f0c118d81334a2bb5f412"
 
+[email protected], source-map@^0.5.0, source-map@^0.5.3, source-map@^0.5.6, source-map@~0.5.1, source-map@~0.5.3:
+  version "0.5.7"
+  resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.5.7.tgz#8a039d2d1021d22d1ea14c80d8ea468ba2ef3fcc"
+
 source-map@^0.4.4:
   version "0.4.4"
   resolved "https://registry.yarnpkg.com/source-map/-/source-map-0.4.4.tgz#eba4f5da9c0dc999de68032d8b4f76173652036b"