Bump acorn from 6.2.1 to 6.4.1

Bumps [acorn](https://github.com/acornjs/acorn) from 6.2.1 to 6.4.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/6.2.1...6.4.1)

Signed-off-by: dependabot[bot] <support@github.com>

package-lock.json

@@ -2792,9 +2792,9 @@
       }
     },
     "acorn": {
-      "version": "6.2.1",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.2.1.tgz",
-      "integrity": "sha512-JD0xT5FCRDNyjDda3Lrg/IxFscp9q4tiYtxE1/nOzlKCk7hIRuYjhq1kCNkbPjMRMZuFq20HNQn1I9k8Oj0E+Q==",
+      "version": "6.4.1",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.4.1.tgz",
+      "integrity": "sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==",
       "dev": true
     },
     "acorn-jsx": {
@@ -11961,7 +11961,7 @@
     },
     "readable-stream": {
       "version": "1.0.34",
-      "resolved": "http://registry.npmjs.org/readable-stream/-/readable-stream-1.0.34.tgz",
+      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-1.0.34.tgz",
       "integrity": "sha1-Elgg40vIQtLyqq+v5MKRbuMsFXw=",
       "dev": true,
       "requires": {

package.json

@@ -28,7 +28,7 @@
     "@babel/core": "^7.5.5",
     "@babel/runtime": "^7.5.5",
     "@svgr/webpack": "^4.3.2",
-    "acorn": "^6.2.1",
+    "acorn": "^6.4.1",
     "ajv": "^6.10.2",
     "babel-core": "7.0.0-bridge.0",
     "babel-eslint": "^10.0.2",