Move performance.now polyfill to ReactDOMFrameScheduling

Author: acdlite

src/renderers/art/ReactARTFiberEntry.js

@@ -534,10 +534,7 @@ const ARTRenderer = ReactFiberReconciler({
     );
   },
 
-  now(): number {
-    // TODO: Enable expiration by implementing this method.
-    return 0;
-  },
+  now: ReactDOMFrameScheduling.now,
 
   useSyncScheduling: true,
 });

src/renderers/dom/fiber/ReactDOMFiberEntry.js

@@ -165,22 +165,6 @@ function shouldAutoFocusHostComponent(type: string, props: Props): boolean {
   return false;
 }
 
-// TODO: Better polyfill
-let now;
-if (
-  typeof window !== 'undefined' &&
-  window.performance &&
-  typeof window.performance.now === 'function'
-) {
-  now = function() {
-    return performance.now();
-  };
-} else {
-  now = function() {
-    return Date.now();
-  };
-}
-
 var DOMRenderer = ReactFiberReconciler({
   getRootHostContext(rootContainerInstance: Container): HostContext {
     let type;
@@ -449,7 +433,7 @@ var DOMRenderer = ReactFiberReconciler({
     }
   },
 
-  now,
+  now: ReactDOMFrameScheduling.now,
 
   canHydrateInstance(
     instance: Instance | TextInstance,

src/renderers/shared/ReactDOMFrameScheduling.js

@@ -39,6 +39,13 @@ if (__DEV__) {
   }
 }
 
+let now: () => number;
+if (typeof performance === 'object' && typeof performance.now === 'function') {
+  now = performance.now.bind(performance);
+} else {
+  now = Date.now;
+}
+
 // TODO: There's no way to cancel, because Fiber doesn't atm.
 let rIC: (callback: (deadline: Deadline) => void) => number;
 
@@ -70,17 +77,11 @@ if (!ExecutionEnvironment.canUseDOM) {
   var activeFrameTime = 33;
 
   var frameDeadlineObject = {
-    timeRemaining: typeof performance === 'object' &&
-      typeof performance.now === 'function'
-      ? function() {
-          // We assume that if we have a performance timer that the rAF callback
-          // gets a performance timer value. Not sure if this is always true.
-          return frameDeadline - performance.now();
-        }
-      : function() {
-          // As a fallback we use Date.now.
-          return frameDeadline - Date.now();
-        },
+    timeRemaining() {
+      // We assume that if we have a performance timer that the rAF callback
+      // gets a performance timer value. Not sure if this is always true.
+      return frameDeadline - now();
+    },
   };
 
   // We use the postMessage trick to defer idle work until after the repaint.
@@ -155,4 +156,5 @@ if (!ExecutionEnvironment.canUseDOM) {
   rIC = requestIdleCallback;
 }
 
+exports.now = now;
 exports.rIC = rIC;