Move walkTree export to react-apollo/walkTree, to avoid bundling it.

Changelog.md

@@ -6,6 +6,14 @@
 
 ### Improvements
 
+- The `walkTree` function has been deprecated, since there's no way to
+  make its behavior consistent with the latest versions of React. To save
+  bundle size, `walkTree` is no longer exported from `react-apollo`,
+  though you can still access it as follows:
+  ```js
+  import { walkTree } from "react-apollo/walkTree"
+  ```
+
 ## 2.3.3
 
 ### Bug Fixes

rollup.config.js

@@ -44,6 +44,9 @@ export default [
   // for test-links
   umd("lib/test-links.js",
       "lib/test-links.js"),
+  // Enable `import { walkTree } from "react-apollo/walkTree"`
+  umd("lib/walkTree.js",
+      "lib/walkTree.js"),
   // for filesize
   {
     input: 'lib/react-apollo.browser.umd.js',

src/browser.ts

@@ -26,6 +26,4 @@ export * from './withApollo';
 
 export * from './types';
 
-export * from './walkTree';
-
 export { compose } from './utils/flowRight';

test/client/getDataFromTree.test.tsx

@@ -6,12 +6,12 @@ import {
   graphql,
   Query,
   ApolloProvider,
-  walkTree,
   getDataFromTree,
   getMarkupFromTree,
   DataValue,
   ChildProps,
 } from '../../src';
+import { walkTree } from "../../src/walkTree";
 import gql from 'graphql-tag';
 const times = require('lodash.times');
 import { InMemoryCache as Cache } from 'apollo-cache-inmemory';