Cache constants for MP Home NativeModules

Summary: TurboModules doesn't cache invocations of getConstants(). This diff looks at which NativeModules' getConstants() methods gets repeated called in Marketplace, and caches those invocations in JS.

Reviewed By: fkgozali

Differential Revision: D21874124

fbshipit-source-id: 03d2318e1b6d00236ef707f9f19a640bf8c08786

Libraries/Utilities/NativeDeviceInfo.js

@@ -43,7 +43,18 @@ export interface Spec extends TurboModule {
 }
 
 const NativeModule: Spec = TurboModuleRegistry.getEnforcing<Spec>('DeviceInfo');
+let constants = null;
 
-const NativeDeviceInfo = NativeModule;
+const NativeDeviceInfo = {
+  getConstants(): {|
+    +Dimensions: DimensionsPayload,
+    +isIPhoneX_deprecated?: boolean,
+  |} {
+    if (constants == null) {
+      constants = NativeModule.getConstants();
+    }
+    return constants;
+  },
+};
 
 export default NativeDeviceInfo;