npm run build fails on master

[crismali]

Steps to reproduce

1. git clone git@github.com:facebook/relay.git
2. cd relay
3. yarn install

npm run build/gulp is run as part of the post-install and fails with:

stream.js:74
      throw er; // Unhandled stream error in pipe.
      ^
Error: ./lib/deepFreeze.js
Module not found: Error: Cannot resolve 'file' or 'directory' ./babel-runtime/core-js/object/is-frozen in /Users/Michael/Development/relay/lib
resolve file
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.webpack.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.web.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.json doesn't exist
resolve directory
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen doesn't exist (directory default file)
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen/package.json doesn't exist (directory description file)
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.webpack.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.web.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/is-frozen.json]
 @ ./lib/deepFreeze.js 22:40-91./lib/deepFreeze.js
Module not found: Error: Cannot resolve 'file' or 'directory' ./babel-runtime/core-js/object/get-own-property-names in /Users/Michael/Development/relay/lib
resolve file
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.webpack.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.web.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.json doesn't exist
resolve directory
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names doesn't exist (directory default file)
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names/package.json doesn't exist (directory description file)
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.webpack.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.web.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/object/get-own-property-names.json]
 @ ./lib/deepFreeze.js 24:51-115./lib/RelayGraphQLTag.js
Module not found: Error: Cannot resolve 'file' or 'directory' ./babel-runtime/core-js/weak-map in /Users/Michael/Development/relay/lib
resolve file
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.webpack.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.web.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.js doesn't exist
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.json doesn't exist
resolve directory
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map doesn't exist (directory default file)
  /Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map/package.json doesn't exist (directory description file)
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.webpack.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.web.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.js]
[/Users/Michael/Development/relay/lib/babel-runtime/core-js/weak-map.json]
 @ ./lib/RelayGraphQLTag.js 17:39-82

Before it fails it displays some warnings as well:

        You or one of the Babel plugins you are using are using Flow declarations as bindings.
        Support for this will be removed in version 6.8. To find out the caller, grep for this
        message and change it to a `console.trace()`.


        You or one of the Babel plugins you are using are using Flow declarations as bindings.
        Support for this will be removed in version 6.8. To find out the caller, grep for this
        message and change it to a `console.trace()`.

A regular npm run build fails in the same way. npm run build works at the v0.10.0 tag but outputs the same warnings.

I know in the contributing guide it says that master is unsafe but that seems to be more geared towards API stability rather than just flat out not being able to build.

[josephsavona]

Thanks for reporting this. You're correct that in general we try to keep master building cleanly. At the moment we're iterating quickly on the core and so things are likely to break briefly while we sort through configuration in different environments.