Revert "android build: Use our patched react-native-webview to cut noise in log."

This reverts commit 1982f3f.

`react-native-webview` relies on a `lib/` directory which is not
automatically built, but instead usually downloaded from `npm`.
Since the source repo doesn't contain `lib/`, this breaks the build.

As this is presently only cosmetic, reverting until either we figure
out how to build it as needed, or (per the previous commit) update
`react-native`.

Author: rk-for-zulip

package.json

@@ -62,7 +62,7 @@
     "react-native-sound": "^0.10.9",
     "react-native-text-input-reset": "^1.0.2",
     "react-native-vector-icons": "^4.6.0",
-    "react-native-webview": "git://github.com/zulip/react-native-webview#49aca8206",
+    "react-native-webview": "^5.0.0",
     "react-navigation": "^2.18.3",
     "react-navigation-redux-helpers": "^2.0.9",
     "react-navigation-tabs": "0.8.4",

yarn.lock

@@ -7771,9 +7771,10 @@ react-native-vector-icons@^4.6.0:
     prop-types "^15.5.10"
     yargs "^8.0.2"
 
-"react-native-webview@git://github.com/zulip/react-native-webview#49aca8206":
+react-native-webview@^5.0.0:
   version "5.12.1"
-  resolved "git://github.com/zulip/react-native-webview#49aca8206f0f05dc17d7bafc96a2886dadec32b3"
+  resolved "https://registry.yarnpkg.com/react-native-webview/-/react-native-webview-5.12.1.tgz#5e2b124e9087d64fc40040d911c10ee5744b5d4d"
+  integrity sha512-pFYzyNUG+k7Jk2a0Z3S1+OL9qtp0VQxVP08d1ume/O6l1Xibi0K0hRZms7zPUHqQc2uWEfjZ0FOa17MIN7vruw==
   dependencies:
     escape-string-regexp "1.0.5"
     invariant "2.2.4"