script: Remove some proprietary Servo-only testing methods from Window (#42728)

These three methods date back from the very early history of Servo and
are no longer necessary:

1. `Window.debug`: `console.log` is a better replacement for this method
   now. A manual test that tests the very basics of JavaScript used
   this. This test is removed as well.
2. `Window.gc`: This can be replaced with `TestUtils.gc`, which is part
    of a W3C specification.
3. `Window.js_backtrace`: This method is moved to `ServoTestUtils`.

Testing: Tests are updated to reflect these changes.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/script/dom/testing/servotestutils.rs

@@ -4,6 +4,7 @@
 
 // check-tidy: no specs after this line
 
+use backtrace::Backtrace;
 use dom_struct::dom_struct;
 use layout_api::ReflowPhasesRun;
 use script_bindings::codegen::GenericBindings::WindowBinding::WindowMethods;
@@ -57,6 +58,12 @@ impl ServoTestUtilsMethods<crate::DomTypeHolder> for ServoTestUtils {
         LayoutResult::new(global, phases, can_gc)
     }
 
+    fn Js_backtrace(_: &GlobalScope) {
+        println!("Current JS stack:");
+        let rust_stack = Backtrace::new();
+        println!("Current Rust stack:\n{:?}", rust_stack);
+    }
+
     fn Panic(_: &GlobalScope) {
         panic!("explicit panic from script")
     }

components/script/dom/testing/testbinding.rs

@@ -17,7 +17,6 @@ use js::realm::CurrentRealm;
 use js::rust::{CustomAutoRooterGuard, HandleObject, HandleValue, MutableHandleValue};
 use js::typedarray::{self, HeapUint8ClampedArray};
 use script_bindings::cformat;
-use script_bindings::codegen::GenericBindings::WindowBinding::WindowMethods;
 use script_bindings::interfaces::TestBindingHelpers;
 use script_bindings::record::Record;
 use servo_config::prefs;
@@ -569,7 +568,7 @@ impl TestBindingMethods<crate::DomTypeHolder> for TestBinding {
         &self,
         _dictionary: RootedTraceableBox<TestDictionaryWithTypedArray>,
     ) {
-        self.global().as_window().Gc();
+        self.global().as_window().gc();
     }
     fn ReceiveTestDictionaryWithSuccessOnKeyword(&self) -> RootedTraceableBox<TestDictionary> {
         RootedTraceableBox::new(TestDictionary {

components/script/dom/window.rs

@@ -15,7 +15,6 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use app_units::Au;
-use backtrace::Backtrace;
 use base::cross_process_instant::CrossProcessInstant;
 use base::generic_channel::{self, GenericCallback, GenericSender};
 use base::id::{BrowsingContextId, PipelineId, WebViewId};
@@ -942,6 +941,13 @@ impl Window {
             }),
         }
     }
+
+    #[expect(unsafe_code)]
+    pub(crate) fn gc(&self) {
+        unsafe {
+            JS_GC(*self.get_cx(), GCReason::API);
+        }
+    }
 }
 
 #[derive(Debug)]
@@ -1771,27 +1777,6 @@ impl WindowMethods<crate::DomTypeHolder> for Window {
     }
 
     // check-tidy: no specs after this line
-    fn Debug(&self, message: DOMString) {
-        debug!("{}", message);
-    }
-
-    #[expect(unsafe_code)]
-    fn Gc(&self) {
-        unsafe {
-            JS_GC(*self.get_cx(), GCReason::API);
-        }
-    }
-
-    #[expect(unsafe_code)]
-    fn Js_backtrace(&self) {
-        unsafe {
-            println!("Current JS stack:");
-            dump_js_stack(*self.get_cx());
-            let rust_stack = Backtrace::new();
-            println!("Current Rust stack:\n{:?}", rust_stack);
-        }
-    }
-
     fn WebdriverCallback(&self, realm: &mut CurrentRealm, value: HandleValue) {
         let webdriver_script_sender = self.webdriver_script_chan.borrow_mut().take();
         if let Some(webdriver_script_sender) = webdriver_script_sender {
@@ -3358,7 +3343,7 @@ impl Window {
         // GC any unreachable objects generated by user script,
         // or unattached DOM nodes. Attached DOM nodes can't be GCd yet,
         // as the document might be reactivated later.
-        self.Gc();
+        self.gc();
     }
 
     pub(crate) fn resume(&self, can_gc: CanGc) {

components/script_bindings/webidls/ServoTestUtils.webidl

@@ -17,6 +17,8 @@ namespace ServoTestUtils {
   [Exposed=Window]
   LayoutResult forceLayout();
 
+  undefined js_backtrace();
+
   undefined panic();
 };
 

components/script_bindings/webidls/Window.webidl

@@ -135,16 +135,6 @@ partial interface Window {
   [Replaceable] readonly attribute double devicePixelRatio;
 };
 
-// Proprietary extensions.
-partial interface Window {
-  [Pref="dom_servo_helpers_enabled"]
-  undefined debug(DOMString arg);
-  [Pref="dom_servo_helpers_enabled"]
-  undefined gc();
-  [Pref="dom_servo_helpers_enabled"]
-  undefined js_backtrace();
-};
-
 // WebDriver extensions
 partial interface Window {
   // Shouldn't be public, but just to make things work for now

components/servo/tests/multiprocess.rs

@@ -29,7 +29,7 @@ fn test_multiprocess_preference_observer() {
         .delegate(delegate.clone())
         .build();
 
-    let result = evaluate_javascript(&servo_test, webview.clone(), "window.gc");
+    let result = evaluate_javascript(&servo_test, webview.clone(), "window.ServoTestUtils");
     assert_eq!(result, Ok(JSValue::Undefined));
 
     let mut prefs = prefs::get().clone();
@@ -40,7 +40,7 @@ fn test_multiprocess_preference_observer() {
     webview.reload();
     servo_test.spin(move || !delegate.load_status_changed.get());
 
-    let result = evaluate_javascript(&servo_test, webview.clone(), "window.gc");
+    let result = evaluate_javascript(&servo_test, webview.clone(), "window.ServoTestUtils");
     assert!(matches!(result, Ok(JSValue::Object(..))));
 }
 

tests/html/test-js.html

@@ -1,25 +0,0 @@
-<div>
-  <img></img>
-  <div>
-    <img></img><img></img><img></img>
-  </div>
-</div>
-<script>
-debug("hi");
-var elem = document.documentElement;
-debug("document.documentElement: " + elem);
-debug("Document: " + Document);
-debug("Node: " + Node);
-debug("Document instanceof Node: " + (Document instanceof Node));
-debug("elem instanceof Node: " + (elem instanceof Node));
-debug("elem instanceof Document: " + (elem instanceof Document));
-debug("document instanceof Document: " + (document instanceof Document));
-debug("document instanceof Node: " + (document instanceof Node));
-debug("elem.tagName: " + elem.tagName);
-debug("elem.firstChild: " + elem.firstChild);
-debug("elem.firstChild.tagName: " + elem.firstChild.tagName);
-debug("elem.firstChild.nextSibling: " + elem.firstChild.nextSibling);
-debug("elem.firstChild.nextSibling.tagName: " + elem.firstChild.nextSibling.tagName);
-debug("elem.nextSibling: " + elem.nextSibling);
-debug("elem.nextSibling.tagName: " + elem.nextSibling.tagName);
-</script>

tests/html/test.js

@@ -1 +0,0 @@
-debug("Hello, world!");

tests/wpt/mozilla/meta/MANIFEST.json

@@ -14226,7 +14226,7 @@
      ]
     ],
     "media_query_list_gc.html": [
-     "36c13b5305e79f216375c384594374f2606797ea",
+     "c24500e1674b802883e4a33bdfa7823a218c81b9",
      [
       null,
       {}
@@ -14510,14 +14510,14 @@
      ]
     ],
     "promise.html": [
-     "5925047287175f291c07ee88075359ed92a86e6a",
+     "c4ce6b3ae93bbe78749f7304a2a966e5888ddd71",
      [
       null,
       {}
      ]
     ],
     "prototypes.html": [
-     "478b89a6fb876477711c19e392d7e4d190bff7a0",
+     "1d145bdd0f8540a68015fead0c93189edee157ad",
      [
       null,
       {}
@@ -14735,7 +14735,7 @@
      ]
     ],
     "trace_null.html": [
-     "bb4f8c1fc52af604a16bf01b198e5ba2857fdbe9",
+     "6a1eae5b741b13efff8bbced5a36b9f52558979d",
      [
       null,
       {}
@@ -14749,7 +14749,7 @@
      ]
     ],
     "transitionend_safety.html": [
-     "b72766c357af9553f1f7411b8d27c404f1e3fcde",
+     "c993fbc61cd4d604b5dde050d308884bd409ff79",
      [
       null,
       {}
@@ -14793,7 +14793,7 @@
      ]
     ],
     "weakref.html": [
-     "4deccbe1e26a3f921eea85a4395394a55cc88be4",
+     "091ff3e67e2999c54fc6e9ee95f7fd331f94501a",
      [
       null,
       {}

tests/wpt/mozilla/tests/mozilla/media_query_list_gc.html

@@ -4,10 +4,10 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script>
-test(function() {
+promise_test(async function() {
   var mql = matchMedia("(min-width: 1000px)");
   mql = null;
-  gc();
+  await TestUtils.gc();
   window.resizeBy(1,1);
 })
 </script>

tests/wpt/mozilla/tests/mozilla/promise.html

@@ -52,13 +52,15 @@
       });
   }, 'Native reject callback gets argument');
 
-  promise_test(function(test) {
+  promise_test(async function(test) {
       var t = new TestBinding;
       var resolved;
       var p = new Promise(function() {});
       var start = Date.now();
       t.resolvePromiseDelayed(p, 'success', 100);
-      test.step_timeout(function() { window.gc() }, 0);
+
+      await TestUtils.gc();
+
       return p.then(function(v) {
           var end = Date.now();
           assert_greater_than_equal(end - start, 100);

tests/wpt/mozilla/tests/mozilla/prototypes.html

@@ -7,9 +7,9 @@
 <body>
   <fooá>foo</fooá>
 <script>
-test(function() {
+promise_test(async function() {
   assert_true(window.document instanceof Node, "Should be Node");
-  gc(); // ensure that our document rooting works; subsequent accesses should be valid.
+  await TestUtils.gc(); // ensure that our document rooting works; subsequent accesses should be valid.
   assert_true(window.document instanceof Node, "Should be Node");
   assert_equals(window.document.nodeType, Node.DOCUMENT_NODE);
   assert_true(window.document.documentElement instanceof Node, "Should be Node");

tests/wpt/mozilla/tests/mozilla/trace_null.html

@@ -2,8 +2,8 @@
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script>
-test(function() {
+promise_test(async function() {
   new CustomEvent("foo", { detail: null });
-  gc();
+  await TestUtils.gc();
 });
 </script>

tests/wpt/mozilla/tests/mozilla/transitionend_safety.html

@@ -15,10 +15,10 @@
     t.step_timeout(function() {
       elem.style.color = 'red';
 
-      t.step_timeout(function() {
+      t.step_timeout(async function() {
         document.body.removeChild(elem);
         elem = null;
-        window.gc();
+        await TestUtils.gc();
         t.step_timeout(t.step_func_done(), 100);
       }, 0);
     }, 0);

tests/wpt/mozilla/tests/mozilla/weakref.html

@@ -4,7 +4,7 @@
 <script src="/resources/testharnessreport.js"></script>
 </head>
 <script>
-test(function() {
+promise_test(async function() {
   // We don't use assert_equals() etc here because it somehow
   // keeps hold of its passed arguments, and thus the weak
   // reference is never freed before the end of the test.
@@ -16,11 +16,11 @@ test(function() {
   t.interfaceAttributeWeak = url;
   assert_true(t.interfaceAttributeWeak !== null);
 
-  gc();
+  await TestUtils.gc();
   assert_true(t.interfaceAttributeWeak !== null);
 
   url = null;
-  gc();
+  await TestUtils.gc();
 
   assert_true(t.interfaceAttributeWeak === null);
 }, "Weak references work");