Cache constants for MP Search 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: D21874123

fbshipit-source-id: a44b98b3ac8621f67c9c0f3b7c4003a561d1e15d

Libraries/NativeModules/specs/NativeSourceCode.js

@@ -19,4 +19,19 @@ export interface Spec extends TurboModule {
   |};
 }
 
-export default (TurboModuleRegistry.getEnforcing<Spec>('SourceCode'): Spec);
+const NativeModule = TurboModuleRegistry.getEnforcing<Spec>('SourceCode');
+let constants = null;
+
+const NativeSourceCode = {
+  getConstants(): {|
+    scriptURL: string,
+  |} {
+    if (constants == null) {
+      constants = NativeModule.getConstants();
+    }
+
+    return constants;
+  },
+};
+
+export default NativeSourceCode;