Remove extraneous benchmark dependency (#6222)

AFAIK this dependency isn't being used anywhere so it should be safe to remove it.

package.json

@@ -62,7 +62,6 @@
     "babel-core": "7.0.0-bridge.0",
     "babel-eslint": "9.0.0",
     "babel-jest": "23.6.0",
-    "benchmark": "2.1.4",
     "cheerio": "0.22.0",
     "chromedriver": "2.42.0",
     "clone": "2.1.1",

yarn.lock

@@ -2457,14 +2457,6 @@ before-after-hook@^1.1.0:
   resolved "https://registry.yarnpkg.com/before-after-hook/-/before-after-hook-1.3.2.tgz#7bfbf844ad670aa7a96b5a4e4e15bd74b08ed66b"
   integrity sha512-zyPgY5dgbf99c0uGUjhY4w+mxqEGxPKg9RQDl34VvrVh2bM31lFN+mwR1ZHepq/KA3VCPk1gwJZL6IIJqjLy2w==
 
-[email protected]:
-  version "2.1.4"
-  resolved "https://registry.yarnpkg.com/benchmark/-/benchmark-2.1.4.tgz#09f3de31c916425d498cc2ee565a0ebf3c2a5629"
-  integrity sha1-CfPeMckWQl1JjMLuVloOvzwqVik=
-  dependencies:
-    lodash "^4.17.4"
-    platform "^1.3.3"
-
 bfj@^6.1.1:
   version "6.1.1"
   resolved "https://registry.yarnpkg.com/bfj/-/bfj-6.1.1.tgz#05a3b7784fbd72cfa3c22e56002ef99336516c48"
@@ -9027,11 +9019,6 @@ pkg-dir@^3.0.0:
   dependencies:
     find-up "^3.0.0"
 
-platform@^1.3.3:
-  version "1.3.5"
-  resolved "https://registry.yarnpkg.com/platform/-/platform-1.3.5.tgz#fb6958c696e07e2918d2eeda0f0bc9448d733444"
-  integrity sha512-TuvHS8AOIZNAlE77WUDiR4rySV/VMptyMfcfeoMgs4P8apaZM3JrnbzBiixKUv+XR6i+BXrQh8WAnjaSPFO65Q==
-
 pluralize@^7.0.0:
   version "7.0.0"
   resolved "https://registry.yarnpkg.com/pluralize/-/pluralize-7.0.0.tgz#298b89df8b93b0221dbf421ad2b1b1ea23fc6777"