pass host context to finalizeInitialChildren (facebook#11970)

* pass host context to finalizeInitialChildren

* don't retrieve context an extra time

Author: jquense

packages/react-reconciler/src/ReactFiberCompleteWork.js

@@ -195,6 +195,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
         oldProps: P,
         newProps: P,
         rootContainerInstance: C,
+        currentHostContext: CX,
       ) {
         // TODO: Type this specific to this type of component.
         workInProgress.updateQueue = (updatePayload: any);
@@ -288,6 +289,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
         oldProps: P,
         newProps: P,
         rootContainerInstance: C,
+        currentHostContext: CX,
       ) {
         // If there are no effects associated with this node, then none of our children had any updates.
         // This guarantees that we can reuse all of them.
@@ -315,6 +317,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
               type,
               newProps,
               rootContainerInstance,
+              currentHostContext,
             )
           ) {
             markUpdate(workInProgress);
@@ -369,6 +372,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
         oldProps: P,
         newProps: P,
         rootContainerInstance: C,
+        currentHostContext: CX,
       ) {
         // Noop
       };
@@ -450,6 +454,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
             oldProps,
             newProps,
             rootContainerInstance,
+            currentHostContext,
           );
 
           if (current.ref !== workInProgress.ref) {
@@ -506,6 +511,7 @@ export default function<T, P, I, TI, HI, PI, C, CC, CX, PL>(
                 type,
                 newProps,
                 rootContainerInstance,
+                currentHostContext,
               )
             ) {
               markUpdate(workInProgress);

packages/react-reconciler/src/ReactFiberReconciler.js

@@ -65,6 +65,7 @@ export type HostConfig<T, P, I, TI, HI, PI, C, CC, CX, PL> = {
     type: T,
     props: P,
     rootContainerInstance: C,
+    hostContext: CX,
   ): boolean,
 
   prepareUpdate(