Upgrade: Bump react from 16.10.2 to 16.12.0

Bumps [react](https://github.com/facebook/react/tree/HEAD/packages/react) from 16.10.2 to 16.12.0.
- [Release notes](https://github.com/facebook/react/releases)
- [Changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md)
- [Commits](https://github.com/facebook/react/commits/v16.12.0/packages/react)

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

packages/extension-browser/package.json

@@ -82,7 +82,7 @@
     "proxyquire": "^2.1.3",
     "puppeteer-core": "^2.0.0",
     "raw-loader": "^3.1.0",
-    "react": "^16.10.2",
+    "react": "^16.12.0",
     "react-dom": "^16.12.0",
     "react-syntax-highlighter": "^11.0.2",
     "rimraf": "^3.0.0",

yarn.lock

@@ -9685,10 +9685,10 @@ react-syntax-highlighter@^11.0.2:
     prismjs "^1.8.4"
     refractor "^2.4.1"
 
-react@^16.10.2:
-  version "16.10.2"
-  resolved "https://registry.yarnpkg.com/react/-/react-16.10.2.tgz#a5ede5cdd5c536f745173c8da47bda64797a4cf0"
-  integrity sha512-MFVIq0DpIhrHFyqLU0S3+4dIcBhhOvBE8bJ/5kHPVOVaGdo0KuiQzpcjCPsf585WvhypqtrMILyoE2th6dT+Lw==
+react@^16.12.0:
+  version "16.12.0"
+  resolved "https://registry.yarnpkg.com/react/-/react-16.12.0.tgz#0c0a9c6a142429e3614834d5a778e18aa78a0b83"
+  integrity sha512-fglqy3k5E+81pA8s+7K0/T3DBCF0ZDOher1elBFzF7O6arXJgzyu/FW+COxFvAWXJoJN9KIZbT2LXlukwphYTA==
   dependencies:
     loose-envify "^1.1.0"
     object-assign "^4.1.1"