Firefox support that doesn't work

Results don't seem to be observable from the test

browser_patches/firefox/juggler/protocol/PageHandler.js

@@ -256,6 +256,14 @@ class PageHandler {
     return await this._contentPage.send('disposeObject', options);
   }
 
+  async ['Heap.collectGarbage']() {
+    await new Promise((resolve) => {
+      Cu.schedulePreciseGC(() => {
+        resolve();
+      });
+    });
+  }
+
   async ['Network.getResponseBody']({requestId}) {
     return this._pageNetwork.getResponseBody(requestId);
   }

browser_patches/firefox/juggler/protocol/Protocol.js

@@ -487,6 +487,17 @@ const Browser = {
   },
 };
 
+const Heap = {
+  targets: ['page'],
+  types: {},
+  events: {},
+  methods: {
+    'collectGarbage': {
+      params: {},
+    },
+  },
+};
+
 const Network = {
   targets: ['page'],
   types: networkTypes,
@@ -1002,7 +1013,7 @@ const Accessibility = {
 }
 
 this.protocol = {
-  domains: {Browser, Page, Runtime, Network, Accessibility},
+  domains: {Browser, Heap, Page, Runtime, Network, Accessibility},
 };
 this.checkScheme = checkScheme;
 this.EXPORTED_SYMBOLS = ['protocol', 'checkScheme'];

packages/playwright-core/src/server/firefox/ffPage.ts

@@ -401,7 +401,7 @@ export class FFPage implements PageDelegate {
   }
 
   async forceGarbageCollection(): Promise<void> {
-    // Not supported in Firefox.
+    await this._session.send('Heap.collectGarbage');
   }
 
   async addInitScript(initScript: InitScript, worldName?: string): Promise<void> {

tests/page/page-force-gc.spec.ts

@@ -17,8 +17,6 @@
 import { test as it, expect } from './pageTest';
 
 it('should work', async function({ page, browserName }) {
-  it.skip(browserName === 'firefox', 'forceGarbageCollection is supported only in Chromium and WebKit');
-
   await page.evaluate(() => {
     globalThis.thing = {};
     globalThis.something = new WeakRef(globalThis.thing);