Update dependency @babel/polyfill to v7.4.3 (#7819)

package.json

@@ -211,7 +211,7 @@
   },
   "homepage": "https://github.com/mozilla/addons-frontend#readme",
   "dependencies": {
-    "@babel/polyfill": "7.4.0",
+    "@babel/polyfill": "7.4.3",
     "@loadable/component": "5.6.1",
     "@loadable/server": "5.6.1",
     "base62": "2.0.1",

yarn.lock

@@ -831,7 +831,15 @@
     "@babel/helper-regex" "^7.0.0"
     regexpu-core "^4.1.3"
 
-"@babel/polyfill@7.4.0", "@babel/polyfill@^7.2.5":
+"@babel/polyfill@7.4.3":
+  version "7.4.3"
+  resolved "https://registry.yarnpkg.com/@babel/polyfill/-/polyfill-7.4.3.tgz#332dc6f57b718017c3a8b37b4eea8aa6eeac1187"
+  integrity sha512-rkv8WIvJshA5Ev8iNMGgz5WZkRtgtiPexiT7w5qevGTuT7ZBfM3de9ox1y9JR5/OXb/sWGBbWlHNa7vQKqku3Q==
+  dependencies:
+    core-js "^2.6.5"
+    regenerator-runtime "^0.13.2"
+
+"@babel/polyfill@^7.2.5":
   version "7.4.0"
   resolved "https://registry.yarnpkg.com/@babel/polyfill/-/polyfill-7.4.0.tgz#90f9d68ae34ac42ab4b4aa03151848f536960218"
   integrity sha512-bVsjsrtsDflIHp5I6caaAa2V25Kzn50HKPL6g3X0P0ni1ks+58cPB8Mz6AOKVuRPgaVdq/OwEUc/1vKqX+Mo4A==