Merge pull request #481 from tomkp/dependabot/npm_and_yarn/acorn-5.7.4

chore(deps): [security] bump acorn from 5.7.1 to 5.7.4

Author: wuweiweiwu

yarn.lock

@@ -1076,8 +1076,9 @@ acorn-walk@^6.0.1:
   integrity sha512-7evsyfH1cLOCdAzZAd43Cic04yKydNx0cF+7tiA19p1XnLLPU4dpCQOqpjqwokFe//vS0QqfqqjCS2JkiIs0cA==
 
 acorn@^5.0.0, acorn@^5.7.1:
-  version "5.7.1"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.7.1.tgz#f095829297706a7c9776958c0afc8930a9b9d9d8"
+  version "5.7.4"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-5.7.4.tgz#3e8d8a9947d0599a1796d10225d7432f4a4acf5e"
+  integrity sha512-1D++VG7BhrtvQpNbBzovKNc1FLGGEE/oGe7b9xJm/RFHMBeUaUGpluV9RLjZa47YFdPcDAenEYuq9pQPcMdLJg==
 
 acorn@^6.0.1, acorn@^6.0.4:
   version "6.3.0"