Fix yarn.lock in the hopes of fixing appveyor

Summary:
Appveyor has been failing with errors like

```
yarn install v0.21.3
[1/4] Resolving packages...
[2/4] Fetching packages...
error "babel-plugin-transform-object-rest-spread-6.20.2.tgz": Tarball is not in
network and can not be located in cache
("C:\\projects\\flow\\babel-plugin-transform-object-rest-spread-6.20.2.tgz")
```

Looking at yarn.lock, the dependency in question looks different. I found
anything that resolved without the URL, deleted them, and ran `yarn install`
again.

Reviewed By: mroch

Differential Revision: D4976460

fbshipit-source-id: 150c8b0a6fe0e864ea85fb52d6c3d9a5e778297a

yarn.lock

@@ -216,7 +216,7 @@ babel-plugin-syntax-flow@^6.18.0, babel-plugin-syntax-flow@^6.8.0:
 
 babel-plugin-syntax-object-rest-spread@^6.8.0:
   version "6.13.0"
-  resolved babel-plugin-syntax-object-rest-spread-6.13.0.tgz#fd6536f2bce13836ffa3a5458c4903a597bb3bf5
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-object-rest-spread/-/babel-plugin-syntax-object-rest-spread-6.13.0.tgz#fd6536f2bce13836ffa3a5458c4903a597bb3bf5"
 
 babel-plugin-syntax-trailing-function-commas@^6.8.0:
   version "6.22.0"
@@ -407,11 +407,11 @@ babel-plugin-transform-flow-strip-types@^6.8.0:
     babel-runtime "^6.22.0"
 
 babel-plugin-transform-object-rest-spread@^6.20.2:
-  version "6.20.2"
-  resolved babel-plugin-transform-object-rest-spread-6.20.2.tgz#e816c55bba77b14c16365d87e2ae48c8fd18fc2e
+  version "6.23.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-transform-object-rest-spread/-/babel-plugin-transform-object-rest-spread-6.23.0.tgz#875d6bc9be761c58a2ae3feee5dc4895d8c7f921"
   dependencies:
     babel-plugin-syntax-object-rest-spread "^6.8.0"
-    babel-runtime "^6.20.0"
+    babel-runtime "^6.22.0"
 
 babel-plugin-transform-regenerator@^6.24.1, babel-plugin-transform-regenerator@^6.8.0:
   version "6.24.1"
@@ -475,7 +475,7 @@ babel-register@^6.24.1, babel-register@^6.8.0:
     mkdirp "^0.5.1"
     source-map-support "^0.4.2"
 
-babel-runtime@^6.18.0, babel-runtime@^6.20.0, babel-runtime@^6.22.0:
+babel-runtime@^6.18.0, babel-runtime@^6.22.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-runtime/-/babel-runtime-6.23.0.tgz#0a9489f144de70efb3ce4300accdb329e2fc543b"
   dependencies: