build(deps): bump acorn from 5.7.3 to 5.7.4

Bumps [acorn](https://github.com/acornjs/acorn) from 5.7.3 to 5.7.4.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](https://github.com/acornjs/acorn/compare/5.7.3...5.7.4)

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

package-lock.json

@@ -623,9 +623,9 @@
       "dev": true
     },
     "acorn": {
-      "version": "5.7.3",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-5.7.3.tgz",
-      "integrity": "sha512-T/zvzYRfbVojPWahDsE5evJdHb3oJoQfFbsrKM7w5Zcs++Tr257tia3BmMP8XYVjp1S9RZXQMh7gao96BlqZOw==",
+      "version": "6.4.1",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.4.1.tgz",
+      "integrity": "sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==",
       "dev": true
     },
     "acorn-globals": {
@@ -636,14 +636,6 @@
       "requires": {
         "acorn": "^6.0.1",
         "acorn-walk": "^6.0.1"
-      },
-      "dependencies": {
-        "acorn": {
-          "version": "6.0.5",
-          "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.0.5.tgz",
-          "integrity": "sha512-i33Zgp3XWtmZBMNvCr4azvOFeWVw1Rk6p3hfi3LUDvIFraOMywb1kAtrbi+med14m4Xfpqm3zRZMT+c0FNE7kg==",
-          "dev": true
-        }
       }
     },
     "acorn-jsx": {
@@ -2709,14 +2701,6 @@
         "acorn": "^6.0.2",
         "acorn-jsx": "^5.0.0",
         "eslint-visitor-keys": "^1.0.0"
-      },
-      "dependencies": {
-        "acorn": {
-          "version": "6.0.5",
-          "resolved": "https://registry.npmjs.org/acorn/-/acorn-6.0.5.tgz",
-          "integrity": "sha512-i33Zgp3XWtmZBMNvCr4azvOFeWVw1Rk6p3hfi3LUDvIFraOMywb1kAtrbi+med14m4Xfpqm3zRZMT+c0FNE7kg==",
-          "dev": true
-        }
       }
     },
     "esprima": {
@@ -5302,6 +5286,14 @@
         "whatwg-url": "^6.4.1",
         "ws": "^5.2.0",
         "xml-name-validator": "^3.0.0"
+      },
+      "dependencies": {
+        "acorn": {
+          "version": "5.7.4",
+          "resolved": "https://registry.npmjs.org/acorn/-/acorn-5.7.4.tgz",
+          "integrity": "sha512-1D++VG7BhrtvQpNbBzovKNc1FLGGEE/oGe7b9xJm/RFHMBeUaUGpluV9RLjZa47YFdPcDAenEYuq9pQPcMdLJg==",
+          "dev": true
+        }
       }
     },
     "jsesc": {