Bump acorn from 6.4.0 to 6.4.1 in /website (#2352)

Summary:
Bumps [acorn](https://github.com/acornjs/acorn) from 6.4.0 to 6.4.1.
<details>
<summary>Commits</summary>
<ul>
<li><a href="https://github.com/acornjs/acorn/commit/9a2e9b6678e243d66846b91179d650d28453e70c"><code>9a2e9b6</code></a> Mark version 6.4.1</li>
<li><a href="https://github.com/acornjs/acorn/commit/90a9548ea0ce351b54f956e2c4ed27cca9631284"><code>90a9548</code></a> More rigorously check surrogate pairs in regexp validator</li>
<li>See full diff in <a href="https://github.com/acornjs/acorn/compare/6.4.0...6.4.1">compare view</a></li>
</ul>
</details>
<br />

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</details>
Pull Request resolved: #2352

Reviewed By: claudiopro

Differential Revision: D20593689

Pulled By: mrkev

fbshipit-source-id: d07e517b8988b437690596d782f9de552828f948

website/yarn.lock

@@ -1312,9 +1312,9 @@ acorn-walk@^6.1.1:
   integrity sha512-7evsyfH1cLOCdAzZAd43Cic04yKydNx0cF+7tiA19p1XnLLPU4dpCQOqpjqwokFe//vS0QqfqqjCS2JkiIs0cA==
 
 acorn@^6.0.7, acorn@^6.2.1:
-  version "6.4.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.0.tgz#b659d2ffbafa24baf5db1cdbb2c94a983ecd2784"
-  integrity sha512-gac8OEcQ2Li1dxIEWGZzsp2BitJxwkwcOm0zHAJLcPJaVvm58FRnk6RkuLRpU1EujipU2ZFODv2P9DLMfnV8mw==
+  version "6.4.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
+  integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
 address@1.1.2, address@^1.0.1:
   version "1.1.2"