diff --git a/.eslintrc.js b/.eslintrc.js
index 414adb07f9338..0bc90137a5c7d 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -26,11 +26,8 @@ module.exports = {
 
   parser: 'babel-eslint',
   parserOptions: {
-    ecmaVersion: 8,
+    ecmaVersion: 9,
     sourceType: 'script',
-    ecmaFeatures: {
-      experimentalObjectRestSpread: true,
-    },
   },
 
   // We're stricter than the default config, mostly. We'll override a few rules
@@ -248,36 +245,36 @@ module.exports = {
         'packages/react-server-native-relay/**/*.js',
       ],
       globals: {
-        nativeFabricUIManager: true,
+        nativeFabricUIManager: 'readonly',
       },
     },
     {
       files: ['packages/react-server-dom-webpack/**/*.js'],
       globals: {
-        __webpack_chunk_load__: true,
-        __webpack_require__: true,
+        __webpack_chunk_load__: 'readonly',
+        __webpack_require__: 'readonly',
       },
     },
     {
       files: ['packages/scheduler/**/*.js'],
       globals: {
-        TaskController: true,
+        TaskController: 'readonly',
       },
     },
   ],
 
   globals: {
-    spyOnDev: true,
-    spyOnDevAndProd: true,
-    spyOnProd: true,
-    __EXPERIMENTAL__: true,
-    __EXTENSION__: true,
-    __PROFILE__: true,
-    __TEST__: true,
-    __UMD__: true,
-    __VARIANT__: true,
-    gate: true,
-    trustedTypes: true,
-    IS_REACT_ACT_ENVIRONMENT: true,
+    spyOnDev: 'readonly',
+    spyOnDevAndProd: 'readonly',
+    spyOnProd: 'readonly',
+    __EXPERIMENTAL__: 'readonly',
+    __EXTENSION__: 'readonly',
+    __PROFILE__: 'readonly',
+    __TEST__: 'readonly',
+    __UMD__: 'readonly',
+    __VARIANT__: 'readonly',
+    gate: 'readonly',
+    trustedTypes: 'readonly',
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
 };
diff --git a/scripts/rollup/validate/eslintrc.cjs.js b/scripts/rollup/validate/eslintrc.cjs.js
index e75f5967eeaf7..45b7a41e7e596 100644
--- a/scripts/rollup/validate/eslintrc.cjs.js
+++ b/scripts/rollup/validate/eslintrc.cjs.js
@@ -7,45 +7,45 @@ module.exports = {
   },
   globals: {
     // ES 6
-    Map: true,
-    Set: true,
-    Proxy: true,
-    Symbol: true,
-    WeakMap: true,
-    WeakSet: true,
-    Uint16Array: true,
-    Reflect: true,
-    globalThis: true,
+    Map: 'readonly',
+    Set: 'readonly',
+    Proxy: 'readonly',
+    Symbol: 'readonly',
+    WeakMap: 'readonly',
+    WeakSet: 'readonly',
+    Uint16Array: 'readonly',
+    Reflect: 'readonly',
+    globalThis: 'readonly',
     // Vendor specific
-    MSApp: true,
-    __REACT_DEVTOOLS_GLOBAL_HOOK__: true,
+    MSApp: 'readonly',
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: 'readonly',
     // CommonJS / Node
-    process: true,
-    setImmediate: true,
-    Buffer: true,
+    process: 'readonly',
+    setImmediate: 'readonly',
+    Buffer: 'readonly',
     // Trusted Types
-    trustedTypes: true,
+    trustedTypes: 'readonly',
 
     // Scheduler profiling
-    Int32Array: true,
-    ArrayBuffer: true,
+    Int32Array: 'readonly',
+    ArrayBuffer: 'readonly',
 
-    TaskController: true,
+    TaskController: 'readonly',
 
     // Flight
-    Uint8Array: true,
-    Promise: true,
+    Uint8Array: 'readonly',
+    Promise: 'readonly',
 
     // Flight Webpack
-    __webpack_chunk_load__: true,
-    __webpack_require__: true,
+    __webpack_chunk_load__: 'readonly',
+    __webpack_require__: 'readonly',
 
     // jest
-    expect: true,
-    jest: true,
+    expect: 'readonly',
+    jest: 'readonly',
 
     // act
-    IS_REACT_ACT_ENVIRONMENT: true,
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
   parserOptions: {
     ecmaVersion: 5,
diff --git a/scripts/rollup/validate/eslintrc.cjs2015.js b/scripts/rollup/validate/eslintrc.cjs2015.js
index 721dd9b026bf1..7135a5a706cff 100644
--- a/scripts/rollup/validate/eslintrc.cjs2015.js
+++ b/scripts/rollup/validate/eslintrc.cjs2015.js
@@ -7,44 +7,44 @@ module.exports = {
   },
   globals: {
     // ES 6
-    Map: true,
-    Set: true,
-    Proxy: true,
-    Symbol: true,
-    WeakMap: true,
-    WeakSet: true,
-    Uint16Array: true,
-    Reflect: true,
+    Map: 'readonly',
+    Set: 'readonly',
+    Proxy: 'readonly',
+    Symbol: 'readonly',
+    WeakMap: 'readonly',
+    WeakSet: 'readonly',
+    Uint16Array: 'readonly',
+    Reflect: 'readonly',
     // Vendor specific
-    MSApp: true,
-    __REACT_DEVTOOLS_GLOBAL_HOOK__: true,
+    MSApp: 'readonly',
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: 'readonly',
     // CommonJS / Node
-    process: true,
-    setImmediate: true,
-    Buffer: true,
+    process: 'readonly',
+    setImmediate: 'readonly',
+    Buffer: 'readonly',
     // Trusted Types
-    trustedTypes: true,
+    trustedTypes: 'readonly',
 
     // Scheduler profiling
-    Int32Array: true,
-    ArrayBuffer: true,
+    Int32Array: 'readonly',
+    ArrayBuffer: 'readonly',
 
-    TaskController: true,
+    TaskController: 'readonly',
 
     // Flight
-    Uint8Array: true,
-    Promise: true,
+    Uint8Array: 'readonly',
+    Promise: 'readonly',
 
     // Flight Webpack
-    __webpack_chunk_load__: true,
-    __webpack_require__: true,
+    __webpack_chunk_load__: 'readonly',
+    __webpack_require__: 'readonly',
 
     // jest
-    expect: true,
-    jest: true,
+    expect: 'readonly',
+    jest: 'readonly',
 
     // act
-    IS_REACT_ACT_ENVIRONMENT: true,
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
   parserOptions: {
     ecmaVersion: 2015,
diff --git a/scripts/rollup/validate/eslintrc.esm.js b/scripts/rollup/validate/eslintrc.esm.js
index bbc94a7f4ee25..34cde555478ab 100644
--- a/scripts/rollup/validate/eslintrc.esm.js
+++ b/scripts/rollup/validate/eslintrc.esm.js
@@ -7,44 +7,44 @@ module.exports = {
   },
   globals: {
     // ES 6
-    Map: true,
-    Set: true,
-    Proxy: true,
-    Symbol: true,
-    WeakMap: true,
-    WeakSet: true,
-    Uint16Array: true,
-    Reflect: true,
+    Map: 'readonly',
+    Set: 'readonly',
+    Proxy: 'readonly',
+    Symbol: 'readonly',
+    WeakMap: 'readonly',
+    WeakSet: 'readonly',
+    Uint16Array: 'readonly',
+    Reflect: 'readonly',
     // Vendor specific
-    MSApp: true,
-    __REACT_DEVTOOLS_GLOBAL_HOOK__: true,
+    MSApp: 'readonly',
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: 'readonly',
     // CommonJS / Node
-    process: true,
-    setImmediate: true,
-    Buffer: true,
+    process: 'readonly',
+    setImmediate: 'readonly',
+    Buffer: 'readonly',
     // Trusted Types
-    trustedTypes: true,
+    trustedTypes: 'readonly',
 
     // Scheduler profiling
-    Int32Array: true,
-    ArrayBuffer: true,
+    Int32Array: 'readonly',
+    ArrayBuffer: 'readonly',
 
-    TaskController: true,
+    TaskController: 'readonly',
 
     // Flight
-    Uint8Array: true,
-    Promise: true,
+    Uint8Array: 'readonly',
+    Promise: 'readonly',
 
     // Flight Webpack
-    __webpack_chunk_load__: true,
-    __webpack_require__: true,
+    __webpack_chunk_load__: 'readonly',
+    __webpack_require__: 'readonly',
 
     // jest
-    expect: true,
-    jest: true,
+    expect: 'readonly',
+    jest: 'readonly',
 
     // act
-    IS_REACT_ACT_ENVIRONMENT: true,
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
   parserOptions: {
     ecmaVersion: 2017,
diff --git a/scripts/rollup/validate/eslintrc.fb.js b/scripts/rollup/validate/eslintrc.fb.js
index bd5881ca47531..d267ca2bec308 100644
--- a/scripts/rollup/validate/eslintrc.fb.js
+++ b/scripts/rollup/validate/eslintrc.fb.js
@@ -7,40 +7,40 @@ module.exports = {
   },
   globals: {
     // ES6
-    Map: true,
-    Set: true,
-    Symbol: true,
-    Proxy: true,
-    WeakMap: true,
-    WeakSet: true,
-    Uint16Array: true,
-    Reflect: true,
+    Map: 'readonly',
+    Set: 'readonly',
+    Symbol: 'readonly',
+    Proxy: 'readonly',
+    WeakMap: 'readonly',
+    WeakSet: 'readonly',
+    Uint16Array: 'readonly',
+    Reflect: 'readonly',
     // Vendor specific
-    MSApp: true,
-    __REACT_DEVTOOLS_GLOBAL_HOOK__: true,
+    MSApp: 'readonly',
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: 'readonly',
     // FB
-    __DEV__: true,
+    __DEV__: 'readonly',
     // Node.js Server Rendering
-    setImmediate: true,
-    Buffer: true,
+    setImmediate: 'readonly',
+    Buffer: 'readonly',
     // Trusted Types
-    trustedTypes: true,
+    trustedTypes: 'readonly',
 
     // Scheduler profiling
-    Int32Array: true,
-    ArrayBuffer: true,
+    Int32Array: 'readonly',
+    ArrayBuffer: 'readonly',
 
-    TaskController: true,
+    TaskController: 'readonly',
 
     // Flight
-    Uint8Array: true,
-    Promise: true,
+    Uint8Array: 'readonly',
+    Promise: 'readonly',
 
     // jest
-    jest: true,
+    jest: 'readonly',
 
     // act
-    IS_REACT_ACT_ENVIRONMENT: true,
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
   parserOptions: {
     ecmaVersion: 5,
diff --git a/scripts/rollup/validate/eslintrc.rn.js b/scripts/rollup/validate/eslintrc.rn.js
index 0f2d7f808da81..e466784e8fcb3 100644
--- a/scripts/rollup/validate/eslintrc.rn.js
+++ b/scripts/rollup/validate/eslintrc.rn.js
@@ -7,36 +7,36 @@ module.exports = {
   },
   globals: {
     // ES6
-    Map: true,
-    Set: true,
-    Symbol: true,
-    Proxy: true,
-    WeakMap: true,
-    WeakSet: true,
-    Reflect: true,
+    Map: 'readonly',
+    Set: 'readonly',
+    Symbol: 'readonly',
+    Proxy: 'readonly',
+    WeakMap: 'readonly',
+    WeakSet: 'readonly',
+    Reflect: 'readonly',
     // Vendor specific
-    MSApp: true,
-    __REACT_DEVTOOLS_GLOBAL_HOOK__: true,
+    MSApp: 'readonly',
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: 'readonly',
     // FB
-    __DEV__: true,
+    __DEV__: 'readonly',
     // Fabric. See https://github.com/facebook/react/pull/15490
     // for more information
-    nativeFabricUIManager: true,
+    nativeFabricUIManager: 'readonly',
     // Trusted Types
-    trustedTypes: true,
+    trustedTypes: 'readonly',
     // RN supports this
-    setImmediate: true,
+    setImmediate: 'readonly',
     // Scheduler profiling
-    Int32Array: true,
-    ArrayBuffer: true,
+    Int32Array: 'readonly',
+    ArrayBuffer: 'readonly',
 
-    TaskController: true,
+    TaskController: 'readonly',
 
     // jest
-    jest: true,
+    jest: 'readonly',
 
     // act
-    IS_REACT_ACT_ENVIRONMENT: true,
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
   parserOptions: {
     ecmaVersion: 5,
diff --git a/scripts/rollup/validate/eslintrc.umd.js b/scripts/rollup/validate/eslintrc.umd.js
index 2077eec029484..2d274375cca8c 100644
--- a/scripts/rollup/validate/eslintrc.umd.js
+++ b/scripts/rollup/validate/eslintrc.umd.js
@@ -6,50 +6,50 @@ module.exports = {
   },
   globals: {
     // ES6
-    Map: true,
-    Set: true,
-    Symbol: true,
-    Proxy: true,
-    WeakMap: true,
-    WeakSet: true,
-    Uint16Array: true,
-    Reflect: true,
+    Map: 'readonly',
+    Set: 'readonly',
+    Symbol: 'readonly',
+    Proxy: 'readonly',
+    WeakMap: 'readonly',
+    WeakSet: 'readonly',
+    Uint16Array: 'readonly',
+    Reflect: 'readonly',
     // Vendor specific
-    MSApp: true,
-    __REACT_DEVTOOLS_GLOBAL_HOOK__: true,
+    MSApp: 'readonly',
+    __REACT_DEVTOOLS_GLOBAL_HOOK__: 'readonly',
     // UMD wrapper code
     // TODO: this is too permissive.
     // Ideally we should only allow these *inside* the UMD wrapper.
-    exports: true,
-    module: true,
-    define: true,
-    require: true,
-    globalThis: true,
-    global: true,
+    exports: 'readonly',
+    module: 'readonly',
+    define: 'readonly',
+    require: 'readonly',
+    globalThis: 'readonly',
+    global: 'readonly',
     // Internet Explorer
-    setImmediate: true,
+    setImmediate: 'readonly',
     // Trusted Types
-    trustedTypes: true,
+    trustedTypes: 'readonly',
 
     // Scheduler profiling
-    Int32Array: true,
-    ArrayBuffer: true,
+    Int32Array: 'readonly',
+    ArrayBuffer: 'readonly',
 
-    TaskController: true,
+    TaskController: 'readonly',
 
     // Flight
-    Uint8Array: true,
-    Promise: true,
+    Uint8Array: 'readonly',
+    Promise: 'readonly',
 
     // Flight Webpack
-    __webpack_chunk_load__: true,
-    __webpack_require__: true,
+    __webpack_chunk_load__: 'readonly',
+    __webpack_require__: 'readonly',
 
     // jest
-    jest: true,
+    jest: 'readonly',
 
     // act
-    IS_REACT_ACT_ENVIRONMENT: true,
+    IS_REACT_ACT_ENVIRONMENT: 'readonly',
   },
   parserOptions: {
     ecmaVersion: 5,