Updates to Prettier 1.19.1 (#2265)

Summary:
**Summary**

Updates `prettier` in dev dependencies to `v1.19.1` to align with the version in use on Facebook's `www` repo. This fixes the [failures in TravisCI lint jobs](https://travis-ci.org/facebook/draft-js/builds/611609545) caused by 6217dc8.

**Test Plan**

Verify there are no lint errors by running the command:
```
yarn lint
```
Pull Request resolved: #2265

Reviewed By: mrkev

Differential Revision: D18748117

Pulled By: claudiopro

fbshipit-source-id: da74d8c36685647ee8841f29fc05aa754eff8ba7

Author: Claudio Procida

meta/bundle-size-stats/Draft.js.json

@@ -73,7 +73,7 @@
     "gulp-rename": "^1.4.0",
     "gulp-util": "^3.0.6",
     "jest": "^24.9.0",
-    "prettier": "1.13.6",
+    "prettier": "1.19.1",
     "react": "^16.8.0",
     "react-dom": "^16.8.0",
     "react-test-renderer": "^16.0.0",

meta/bundle-size-stats/Draft.min.js.json

@@ -5636,7 +5636,7 @@ longest@^1.0.1:
   resolved "https://registry.yarnpkg.com/longest/-/longest-1.0.1.tgz#30a0b2da38f73770e8294a0d22e6625ed77d0097"
   integrity sha1-MKCy2jj3N3DoKUoNIuZiXtd9AJc=
 
-loose-envify@^1.0.0, loose-envify@^1.1.0, loose-envify@^1.4.0:
+loose-envify@^1.0.0, loose-envify@^1.1.0, loose-envify@^1.3.1, loose-envify@^1.4.0:
   version "1.4.0"
   resolved "https://registry.yarnpkg.com/loose-envify/-/loose-envify-1.4.0.tgz#71ee51fa7be4caec1a63839f7e682d8132d30caf"
   integrity sha512-lyuxPGr/Wfhrlem2CL/UcnUc1zcqKAImBDzukY7Y5F/yQiNdko6+fRLevlw1HgMySw7f611UIY408EtxRSoK3Q==
@@ -6857,10 +6857,10 @@ prettier-linter-helpers@^1.0.0:
   dependencies:
     fast-diff "^1.1.2"
 
-prettier@1.13.6:
-  version "1.13.6"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.13.6.tgz#00ae0b777ad92f81a9e7a1df2f0470b6dab0cb44"
-  integrity sha512-p5eqCNiohWZN++7aJXUVj0JgLqHCPLf9GLIcLBHGNWs4Y9FJOPs6+KNO2WT0udJIQJTbeZFrJkjzjcb8fkAYYQ==
+prettier@1.19.1:
+  version "1.19.1"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.19.1.tgz#f7d7f5ff8a9cd872a7be4ca142095956a60797cb"
+  integrity sha512-s7PoyDv/II1ObgQunCbB9PdLmUcBZcnWOcxDh7O0N/UwDEsHyqkW+Qh28jW+mVuCdx7gLB0BotYI1Y6uI9iyew==
 
 pretty-format@^24.9.0:
   version "24.9.0"
@@ -6917,7 +6917,14 @@ prompts@^2.0.1:
     kleur "^3.0.2"
     sisteransi "^1.0.0"
 
-prop-types@^15.6.2, prop-types@^15.7.2:
+prop-types@^15.6.2:
+  version "15.6.2"
+  resolved "https://registry.npmjs.org/prop-types/-/prop-types-15.6.2.tgz#05d5ca77b4453e985d60fc7ff8c859094a497102"
+  dependencies:
+    loose-envify "^1.3.1"
+    object-assign "^4.1.1"
+
+prop-types@^15.7.2:
   version "15.7.2"
   resolved "https://registry.yarnpkg.com/prop-types/-/prop-types-15.7.2.tgz#52c41e75b8c87e72b9d9360e0206b99dcbffa6c5"
   integrity sha512-8QQikdH7//R2vurIJSutZ1smHYTcLpRWEOlHnzcWHmBYrOGUysKwSsrC89BCiFj3CbrfJ/nXFdJepOVrY1GCHQ==
@@ -6933,13 +6940,6 @@ property-information@^5.0.0, property-information@^5.0.1:
   dependencies:
     xtend "^4.0.1"
 
-prop-types@^15.6.2:
-  version "15.6.2"
-  resolved "https://registry.npmjs.org/prop-types/-/prop-types-15.6.2.tgz#05d5ca77b4453e985d60fc7ff8c859094a497102"
-  dependencies:
-    loose-envify "^1.3.1"
-    object-assign "^4.1.1"
-
 prr@~1.0.1:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/prr/-/prr-1.0.1.tgz#d3fc114ba06995a45ec6893f484ceb1d78f5f476"