script: Create a debugger script for the SpiderMonkey Debugger API (#38331)

to use the [SpiderMonkey Debugger
API](https://firefox-source-docs.mozilla.org/js/Debugger/), we need to
call it from an internal debugger script that we will supply. this
script must run in the same runtime as the debuggee(s), but in a
separate
[compartment](https://udn.realityripple.com/docs/Mozilla/Projects/SpiderMonkey/Compartments)
([more
details](https://hacks.mozilla.org/2020/03/future-proofing-firefoxs-javascript-debugger-implementation/)).

this patch defines a new DebuggerGlobalScope type and a new debugger
script resource. when creating each script thread, we create a debugger
global, load the debugger script from resources/debugger.js, and run
that script in the global to initialise the Debugger API.

subsequent patches will use the debugger script as an RPC mechanism for
the Debugger API.

Testing: no testable effects yet, but will be used in #37667
Fixes: part of #36027

---------

Signed-off-by: Delan Azabani <dazabani@igalia.com>
Co-authored-by: atbrakhi <atbrakhi@igalia.com>

components/script_bindings/codegen/Bindings.conf

@@ -166,6 +166,10 @@ DOMInterfaces = {
     'canGc': ['IndexedGetter', 'Add', 'Add_']
 },
 
+'DebuggerGlobalScope': {
+    'useSystemCompartment': True,
+},
+
 'Document': {
     'additionalTraits': ["crate::interfaces::DocumentHelpers"],
     'canGc': ['Close', 'CreateElement', 'CreateElementNS', 'ImportNode', 'SetTitle', 'Write', 'Writeln', 'CreateEvent', 'CreateRange', 'Open', 'Open_', 'CreateComment', 'CreateAttribute', 'CreateAttributeNS', 'CreateDocumentFragment', 'CreateTextNode', 'CreateCDATASection', 'CreateProcessingInstruction', 'Prepend', 'Append', 'ReplaceChildren', 'SetBgColor', 'SetFgColor', 'Fonts', 'ElementFromPoint', 'ElementsFromPoint', 'GetScrollingElement', 'ExitFullscreen', 'CreateExpression', 'CreateNSResolver', 'Evaluate', 'StyleSheets', 'Implementation', 'GetElementsByTagName', 'GetElementsByTagNameNS', 'GetElementsByClassName', 'AdoptNode', 'CreateNodeIterator', 'SetBody', 'GetElementsByName', 'Images', 'Embeds', 'Plugins', 'Links', 'Forms', 'Scripts', 'Anchors', 'Applets', 'Children', 'GetSelection', 'NamedGetter', 'AdoptedStyleSheets'],

components/script_bindings/webidls/DebuggerGlobalScope.webidl

@@ -0,0 +1,9 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// This interface is entirely internal to Servo, and should not be accessible to
+// web pages.
+[Global=DebuggerGlobalScope, Exposed=DebuggerGlobalScope]
+interface DebuggerGlobalScope: GlobalScope {
+};

components/script_bindings/webidls/EventTarget.webidl

@@ -5,7 +5,7 @@
  * https://dom.spec.whatwg.org/#interface-eventtarget
  */
 
-[Exposed=(Window,Worker,Worklet,DissimilarOriginWindow)]
+[Exposed=(Window,Worker,Worklet,DissimilarOriginWindow,DebuggerGlobalScope)]
 interface EventTarget {
   [Throws] constructor();
   undefined addEventListener(

components/script_bindings/webidls/GlobalScope.webidl

@@ -5,6 +5,6 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Exposed=(Window,Worker,Worklet,DissimilarOriginWindow),
+[Exposed=(Window,Worker,Worklet,DissimilarOriginWindow,DebuggerGlobalScope),
  Inline]
 interface GlobalScope : EventTarget {};