Unify context stack implementations (#12359)

* Use module pattern so context stack is isolated per renderer

* Unify context implementations

Implements the new context API on top of the existing ReactStack that we
already use for host context and legacy context. Now there is a single
array that we push and pop from.

This makes the interrupt path slightly slower, since when we reset the
unit of work pointer, we have to iterate over the stack (like before)
*and* switch on the type of work (not like before). On the other hand,
this unifies all of the unwinding behavior in the UnwindWork module.

* Add DEV only warning if stack is not reset properly

packages/react-reconciler/src/ReactFiberBeginWork.js

@@ -11,6 +11,8 @@ import type {HostConfig} from 'react-reconciler';
 import type {ReactProviderType, ReactContext} from 'shared/ReactTypes';
 import type {Fiber} from 'react-reconciler/src/ReactFiber';
 import type {HostContext} from './ReactFiberHostContext';
+import type {LegacyContext} from './ReactFiberContext';
+import type {NewContext} from './ReactFiberNewContext';
 import type {HydrationContext} from './ReactFiberHydrationContext';
 import type {FiberRoot} from './ReactFiberRoot';
 import type {ExpirationTime} from './ReactFiberExpirationTime';
@@ -57,15 +59,6 @@ import {
   cloneChildFibers,
 } from './ReactChildFiber';
 import {processUpdateQueue} from './ReactFiberUpdateQueue';
-import {
-  getMaskedContext,
-  getUnmaskedContext,
-  hasContextChanged as hasLegacyContextChanged,
-  pushContextProvider as pushLegacyContextProvider,
-  pushTopLevelContextObject,
-  invalidateContextProvider,
-} from './ReactFiberContext';
-import {pushProvider} from './ReactFiberNewContext';
 import {NoWork, Never} from './ReactFiberExpirationTime';
 import {AsyncMode, StrictMode} from './ReactTypeOfMode';
 import MAX_SIGNED_31_BIT_INT from './maxSigned31BitInt';
@@ -83,6 +76,8 @@ if (__DEV__) {
 export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
   config: HostConfig<T, P, I, TI, HI, PI, C, CC, CX, PL>,
   hostContext: HostContext<C, CX>,
+  legacyContext: LegacyContext,
+  newContext: NewContext,
   hydrationContext: HydrationContext<C, CX>,
   scheduleWork: (fiber: Fiber, expirationTime: ExpirationTime) => void,
   computeExpirationForFiber: (fiber: Fiber) => ExpirationTime,
@@ -91,6 +86,17 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
 
   const {pushHostContext, pushHostContainer} = hostContext;
 
+  const {pushProvider} = newContext;
+
+  const {
+    getMaskedContext,
+    getUnmaskedContext,
+    hasContextChanged: hasLegacyContextChanged,
+    pushContextProvider: pushLegacyContextProvider,
+    pushTopLevelContextObject,
+    invalidateContextProvider,
+  } = legacyContext;
+
   const {
     enterHydrationState,
     resetHydrationState,
@@ -105,6 +111,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
     resumeMountClassInstance,
     updateClassInstance,
   } = ReactFiberClassComponent(
+    legacyContext,
     scheduleWork,
     computeExpirationForFiber,
     memoizeProps,

packages/react-reconciler/src/ReactFiberClassComponent.js

@@ -9,6 +9,7 @@
 
 import type {Fiber} from './ReactFiber';
 import type {ExpirationTime} from './ReactFiberExpirationTime';
+import type {LegacyContext} from './ReactFiberContext';
 import type {CapturedValue} from './ReactCapturedValue';
 
 import {Update} from 'shared/ReactTypeOfSideEffect';
@@ -29,17 +30,10 @@ import warning from 'fbjs/lib/warning';
 
 import {startPhaseTimer, stopPhaseTimer} from './ReactDebugFiberPerf';
 import {StrictMode} from './ReactTypeOfMode';
-import {
-  cacheContext,
-  getMaskedContext,
-  getUnmaskedContext,
-  isContextConsumer,
-} from './ReactFiberContext';
 import {
   insertUpdateIntoFiber,
   processUpdateQueue,
 } from './ReactFiberUpdateQueue';
-import {hasContextChanged} from './ReactFiberContext';
 
 const fakeInternalInstance = {};
 const isArray = Array.isArray;
@@ -110,11 +104,20 @@ function callGetDerivedStateFromCatch(ctor: any, capturedValues: Array<mixed>) {
 }
 
 export default function(
+  legacyContext: LegacyContext,
   scheduleWork: (fiber: Fiber, expirationTime: ExpirationTime) => void,
   computeExpirationForFiber: (fiber: Fiber) => ExpirationTime,
   memoizeProps: (workInProgress: Fiber, props: any) => void,
   memoizeState: (workInProgress: Fiber, state: any) => void,
 ) {
+  const {
+    cacheContext,
+    getMaskedContext,
+    getUnmaskedContext,
+    isContextConsumer,
+    hasContextChanged,
+  } = legacyContext;
+
   // Class component state updater
   const updater = {
     isMounted,

packages/react-reconciler/src/ReactFiberCompleteWork.js

@@ -11,6 +11,8 @@ import type {HostConfig} from 'react-reconciler';
 import type {Fiber} from './ReactFiber';
 import type {ExpirationTime} from './ReactFiberExpirationTime';
 import type {HostContext} from './ReactFiberHostContext';
+import type {LegacyContext} from './ReactFiberContext';
+import type {NewContext} from './ReactFiberNewContext';
 import type {HydrationContext} from './ReactFiberHydrationContext';
 import type {FiberRoot} from './ReactFiberRoot';
 
@@ -46,15 +48,12 @@ import {
 import invariant from 'fbjs/lib/invariant';
 
 import {reconcileChildFibers} from './ReactChildFiber';
-import {
-  popContextProvider as popLegacyContextProvider,
-  popTopLevelContextObject as popTopLevelLegacyContextObject,
-} from './ReactFiberContext';
-import {popProvider} from './ReactFiberNewContext';
 
 export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
   config: HostConfig<T, P, I, TI, HI, PI, C, CC, CX, PL>,
   hostContext: HostContext<C, CX>,
+  legacyContext: LegacyContext,
+  newContext: NewContext,
   hydrationContext: HydrationContext<C, CX>,
 ) {
   const {
@@ -74,6 +73,13 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
     popHostContainer,
   } = hostContext;
 
+  const {
+    popContextProvider: popLegacyContextProvider,
+    popTopLevelContextObject: popTopLevelLegacyContextObject,
+  } = legacyContext;
+
+  const {popProvider} = newContext;
+
   const {
     prepareToHydrateHostInstance,
     prepareToHydrateHostTextInstance,