Stop importing shallowEqual from fbjs/lib/shallowEqual.

This shaves a tiny amount of bundle size, but more importantly it
implements shallowEqual using TypeScript, and avoids one of the few
remaining uses of require.

package.json

@@ -151,7 +151,6 @@
     "zen-observable-ts": "0.8.13"
   },
   "dependencies": {
-    "fbjs": "^1.0.0",
     "hoist-non-react-statics": "^3.0.0",
     "invariant": "^2.2.2",
     "lodash.isequal": "^4.5.0",

src/Mutation.tsx

@@ -4,7 +4,7 @@ import ApolloClient, { PureQueryOptions, ApolloError, FetchPolicy } from 'apollo
 import { DataProxy } from 'apollo-cache';
 const invariant = require('invariant');
 import { DocumentNode, GraphQLError } from 'graphql';
-const shallowEqual = require('fbjs/lib/shallowEqual');
+import shallowEqual from './utils/shallowEqual';
 
 import { OperationVariables, RefetchQueriesProviderFn } from './types';
 import { parser, DocumentType } from './parser';

src/Query.tsx

@@ -15,7 +15,7 @@ import { parser, DocumentType, IDocumentDefinition } from './parser';
 import { getClient } from './component-utils';
 import { RenderPromises } from './getDataFromTree';
 
-const shallowEqual = require('fbjs/lib/shallowEqual');
+import shallowEqual from './utils/shallowEqual';
 const invariant = require('invariant');
 
 export type ObservableQueryFields<TData, TVariables> = Pick<

src/Subscriptions.tsx

@@ -8,7 +8,7 @@ import { ZenObservable } from 'zen-observable-ts';
 import { OperationVariables } from './types';
 import { getClient } from './component-utils';
 
-const shallowEqual = require('fbjs/lib/shallowEqual');
+import shallowEqual from './utils/shallowEqual';
 const invariant = require('invariant');
 
 export interface SubscriptionResult<TData = any> {

src/queryRecycler.ts

@@ -2,7 +2,7 @@ import { ObservableQuery } from 'apollo-client';
 import { ZenObservable } from 'zen-observable-ts';
 import { QueryOpts } from './types';
 
-const shallowEqual = require('fbjs/lib/shallowEqual');
+import shallowEqual from './utils/shallowEqual';
 
 // XXX move this logic to ObservableQuery / QueryManager in apollo-client
 

src/utils/shallowEqual.ts

@@ -0,0 +1,32 @@
+const { hasOwnProperty } = Object.prototype;
+
+function is(x: any, y: any) {
+  if (x === y) {
+    return x !== 0 || y !== 0 || 1 / x === 1 / y;
+  }
+  return x !== x && y !== y;
+}
+
+function isObject(obj: any): obj is { [key: string]: any } {
+  return obj !== null && typeof obj === "object";
+}
+
+export default function shallowEqual(objA: any, objB: any) {
+  if (is(objA, objB)) {
+    return true;
+  }
+
+  if (!isObject(objA) || !isObject(objB)) {
+    return false;
+  }
+
+  const keys = Object.keys(objA);
+
+  if (keys.length !== Object.keys(objB).length) {
+    return false;
+  }
+
+  return keys.every(
+    key => hasOwnProperty.call(objB, key) && is(objA[key], objB[key]),
+  );
+}