Clean up perf hooks a little

src/javascript/jsc/perf_hooks.exports.js

@@ -1,15 +1,27 @@
 export var performance = globalThis.performance;
 
-export function PerformanceObserver() {
-  throw new Error("PerformanceEntry is not implemented yet");
+export class PerformanceObserver {
+  constructor() {
+    throw new Error("PerformanceEntry is not implemented yet");
+  }
 }
 
-export function PerformanceEntry() {
-  throw new Error("PerformanceEntry is not implemented yet");
+export class PerformanceEntry {
+  constructor() {
+    throw new Error("PerformanceEntry is not implemented yet");
+  }
+}
+export class PerformanceNodeTiming {
+  constructor() {
+    throw new Error(
+      "PerformanceNodeTiming is not supported in this environment."
+    );
+  }
 }
 
-export function PerformanceNodeTiming() {
-  throw new Error(
-    "PerformanceNodeTiming is not supported in this environment."
-  );
-}
+export default {
+  performance,
+  PerformanceEntry,
+  PerformanceEntry,
+  PerformanceNodeTiming,
+};