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diff --git a/js/loader/ScriptLoadRequest.h b/js/loader/ScriptLoadRequest.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef js_loader_ScriptLoadRequest_h
+#define js_loader_ScriptLoadRequest_h
+
+#include "js/AllocPolicy.h"
+#include "js/RootingAPI.h"
+#include "js/SourceText.h"
+#include "js/TypeDecls.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/CORSMode.h"
+#include "mozilla/dom/SRIMetadata.h"
+#include "mozilla/dom/ReferrerPolicyBinding.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/MaybeOneOf.h"
+#include "mozilla/PreloaderBase.h"
+#include "mozilla/StaticPrefs_dom.h"
+#include "mozilla/Utf8.h"  // mozilla::Utf8Unit
+#include "mozilla/Variant.h"
+#include "mozilla/Vector.h"
+#include "nsCOMPtr.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsIGlobalObject.h"
+#include "ScriptKind.h"
+#include "nsIScriptElement.h"
+
+class nsICacheInfoChannel;
+
+namespace mozilla::dom {
+
+class ScriptLoadContext;
+class WorkerLoadContext;
+class WorkletLoadContext;
+
+}  // namespace mozilla::dom
+
+namespace mozilla::loader {
+class ComponentLoadContext;
+}  // namespace mozilla::loader
+
+namespace JS {
+class OffThreadToken;
+
+namespace loader {
+
+using Utf8Unit = mozilla::Utf8Unit;
+
+class LoadContextBase;
+class ModuleLoadRequest;
+class ScriptLoadRequestList;
+
+/*
+ * ScriptFetchOptions loosely corresponds to HTML's "script fetch options",
+ * https://html.spec.whatwg.org/multipage/webappapis.html#script-fetch-options
+ * with the exception of the following properties:
+ *   cryptographic nonce
+ *      The cryptographic nonce metadata used for the initial fetch and for
+ *      fetching any imported modules. As this is populated by a DOM element,
+ *      this is implemented via mozilla::dom::Element as the field
+ *      mElement. The default value is an empty string, and is indicated
+ *      when this field is a nullptr. Nonce is not represented on the dom
+ *      side as per bug 1374612.
+ *   parser metadata
+ *      The parser metadata used for the initial fetch and for fetching any
+ *      imported modules. This is populated from a mozilla::dom::Element and is
+ *      handled by the field mElement. The default value is an empty string,
+ *      and is indicated when this field is a nullptr.
+ *   integrity metadata
+ *      The integrity metadata used for the initial fetch. This is
+ *      implemented in ScriptLoadRequest, as it changes for every
+ *      ScriptLoadRequest.
+ *
+ * In the case of classic scripts without dynamic import, this object is
+ * used once. For modules, this object is propogated throughout the module
+ * tree. If there is a dynamically imported module in any type of script,
+ * the ScriptFetchOptions object will be propogated from its importer.
+ */
+
+class ScriptFetchOptions {
+  ~ScriptFetchOptions();
+
+ public:
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(ScriptFetchOptions)
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ScriptFetchOptions)
+
+  ScriptFetchOptions(mozilla::CORSMode aCORSMode,
+                     enum mozilla::dom::ReferrerPolicy aReferrerPolicy,
+                     nsIPrincipal* aTriggeringPrincipal,
+                     mozilla::dom::Element* aElement = nullptr);
+
+  /*
+   *  The credentials mode used for the initial fetch (for module scripts)
+   *  and for fetching any imported modules (for both module scripts and
+   *  classic scripts)
+   */
+  const mozilla::CORSMode mCORSMode;
+
+  /*
+   *  The referrer policy used for the initial fetch and for fetching any
+   *  imported modules
+   */
+  const enum mozilla::dom::ReferrerPolicy mReferrerPolicy;
+
+  /*
+   *  Used to determine CSP and if we are on the About page.
+   *  Only used in DOM content scripts.
+   *  TODO: Move to ScriptLoadContext
+   */
+  nsCOMPtr<nsIPrincipal> mTriggeringPrincipal;
+  /*
+   *  Represents fields populated by DOM elements (nonce, parser metadata)
+   *  Leave this field as a nullptr for any fetch that requires the
+   *  default classic script options.
+   *  (https://html.spec.whatwg.org/multipage/webappapis.html#default-classic-script-fetch-options)
+   *  TODO: extract necessary fields rather than passing this object
+   */
+  nsCOMPtr<mozilla::dom::Element> mElement;
+};
+
+/*
+ * ScriptLoadRequest
+ *
+ * ScriptLoadRequest is a generic representation of a JavaScript script that
+ * will be loaded by a Script/Module loader. This representation is used by the
+ * DOM ScriptLoader and will be used by workers and MOZJSComponentLoader.
+ *
+ * The ScriptLoadRequest contains information about the kind of script (classic
+ * or module), the URI, and the ScriptFetchOptions associated with the script.
+ * It is responsible for holding the script data once the fetch is complete, or
+ * if the request is cached, the bytecode.
+ *
+ * Relationship to ScriptLoadContext:
+ *
+ * ScriptLoadRequest and ScriptLoadContexts have a circular pointer.  A
+ * ScriptLoadContext augments the loading of a ScriptLoadRequest by providing
+ * additional information regarding the loading and evaluation behavior (see
+ * the ScriptLoadContext class for details).  In terms of responsibility,
+ * the ScriptLoadRequest represents "What" is being loaded, and the
+ * ScriptLoadContext represents "How".
+ *
+ * TODO: see if we can use it in the jsshell script loader. We need to either
+ * remove ISUPPORTS or find a way to encorporate that in the jsshell. We would
+ * then only have one implementation of the script loader, and it would be
+ * tested whenever jsshell tests are run. This would mean finding another way to
+ * create ScriptLoadRequest lists.
+ *
+ */
+
+class ScriptLoadRequest
+    : public nsISupports,
+      private mozilla::LinkedListElement<ScriptLoadRequest> {
+  using super = LinkedListElement<ScriptLoadRequest>;
+
+  // Allow LinkedListElement<ScriptLoadRequest> to cast us to itself as needed.
+  friend class mozilla::LinkedListElement<ScriptLoadRequest>;
+  friend class ScriptLoadRequestList;
+
+ protected:
+  virtual ~ScriptLoadRequest();
+
+ public:
+  using SRIMetadata = mozilla::dom::SRIMetadata;
+  ScriptLoadRequest(ScriptKind aKind, nsIURI* aURI,
+                    ScriptFetchOptions* aFetchOptions,
+                    const SRIMetadata& aIntegrity, nsIURI* aReferrer,
+                    LoadContextBase* aContext);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ScriptLoadRequest)
+
+  using super::getNext;
+  using super::isInList;
+
+  template <typename T>
+  using VariantType = mozilla::VariantType<T>;
+
+  template <typename... Ts>
+  using Variant = mozilla::Variant<Ts...>;
+
+  template <typename T, typename D = JS::DeletePolicy<T>>
+  using UniquePtr = mozilla::UniquePtr<T, D>;
+
+  using MaybeSourceText =
+      mozilla::MaybeOneOf<JS::SourceText<char16_t>, JS::SourceText<Utf8Unit>>;
+
+  bool IsModuleRequest() const { return mKind == ScriptKind::eModule; }
+  bool IsImportMapRequest() const { return mKind == ScriptKind::eImportMap; }
+
+  ModuleLoadRequest* AsModuleRequest();
+  const ModuleLoadRequest* AsModuleRequest() const;
+
+  virtual bool IsTopLevel() const { return true; };
+
+  virtual void Cancel();
+
+  virtual void SetReady();
+
+  enum class State : uint8_t {
+    Fetching,
+    Compiling,
+    LoadingImports,
+    Ready,
+    Canceled
+  };
+
+  bool IsFetching() const { return mState == State::Fetching; }
+  bool IsCompiling() const { return mState == State::Compiling; }
+  bool IsLoadingImports() const { return mState == State::LoadingImports; }
+
+  bool IsReadyToRun() const {
+    return mState == State::Ready || mState == State::Canceled;
+  }
+
+  bool IsCanceled() const { return mState == State::Canceled; }
+
+  // Type of data provided by the nsChannel.
+  enum class DataType : uint8_t { eUnknown, eTextSource, eBytecode };
+
+  bool IsUnknownDataType() const { return mDataType == DataType::eUnknown; }
+  bool IsTextSource() const { return mDataType == DataType::eTextSource; }
+  bool IsSource() const { return IsTextSource(); }
+
+  void SetUnknownDataType() {
+    mDataType = DataType::eUnknown;
+    mScriptData.reset();
+  }
+
+  bool IsUTF8ParsingEnabled();
+
+  void SetTextSource() {
+    MOZ_ASSERT(IsUnknownDataType());
+    mDataType = DataType::eTextSource;
+    if (IsUTF8ParsingEnabled()) {
+      mScriptData.emplace(VariantType<ScriptTextBuffer<Utf8Unit>>());
+    } else {
+      mScriptData.emplace(VariantType<ScriptTextBuffer<char16_t>>());
+    }
+  }
+
+  // Use a vector backed by the JS allocator for script text so that contents
+  // can be transferred in constant time to the JS engine, not copied in linear
+  // time.
+  template <typename Unit>
+  using ScriptTextBuffer = mozilla::Vector<Unit, 0, js::MallocAllocPolicy>;
+
+  bool IsUTF16Text() const {
+    return mScriptData->is<ScriptTextBuffer<char16_t>>();
+  }
+  bool IsUTF8Text() const {
+    return mScriptData->is<ScriptTextBuffer<Utf8Unit>>();
+  }
+
+  template <typename Unit>
+  const ScriptTextBuffer<Unit>& ScriptText() const {
+    MOZ_ASSERT(IsTextSource());
+    return mScriptData->as<ScriptTextBuffer<Unit>>();
+  }
+  template <typename Unit>
+  ScriptTextBuffer<Unit>& ScriptText() {
+    MOZ_ASSERT(IsTextSource());
+    return mScriptData->as<ScriptTextBuffer<Unit>>();
+  }
+
+  size_t ScriptTextLength() const {
+    MOZ_ASSERT(IsTextSource());
+    return IsUTF16Text() ? ScriptText<char16_t>().length()
+                         : ScriptText<Utf8Unit>().length();
+  }
+
+  // Get source text.  On success |aMaybeSource| will contain either UTF-8 or
+  // UTF-16 source; on failure it will remain in its initial state.
+  nsresult GetScriptSource(JSContext* aCx, MaybeSourceText* aMaybeSource);
+
+  void ClearScriptText() {
+    MOZ_ASSERT(IsTextSource());
+    return IsUTF16Text() ? ScriptText<char16_t>().clearAndFree()
+                         : ScriptText<Utf8Unit>().clearAndFree();
+  }
+
+  enum mozilla::dom::ReferrerPolicy ReferrerPolicy() const {
+    return mFetchOptions->mReferrerPolicy;
+  }
+
+  nsIPrincipal* TriggeringPrincipal() const {
+    return mFetchOptions->mTriggeringPrincipal;
+  }
+
+  void ClearScriptSource();
+
+  void MarkForBytecodeEncoding(JSScript* aScript);
+
+  bool IsMarkedForBytecodeEncoding() const;
+
+  bool IsBytecode() const { return mDataType == DataType::eBytecode; }
+
+  void SetBytecode();
+
+  mozilla::CORSMode CORSMode() const { return mFetchOptions->mCORSMode; }
+
+  void DropBytecodeCacheReferences();
+
+  bool HasLoadContext() const { return mLoadContext; }
+  bool HasScriptLoadContext() const;
+  bool HasWorkerLoadContext() const;
+
+  mozilla::dom::ScriptLoadContext* GetScriptLoadContext();
+
+  mozilla::loader::ComponentLoadContext* GetComponentLoadContext();
+
+  mozilla::dom::WorkerLoadContext* GetWorkerLoadContext();
+
+  mozilla::dom::WorkletLoadContext* GetWorkletLoadContext();
+
+  const ScriptKind mKind;  // Whether this is a classic script or a module
+                           // script.
+
+  State mState;           // Are we still waiting for a load to complete?
+  bool mFetchSourceOnly;  // Request source, not cached bytecode.
+  DataType mDataType;     // Does this contain Source or Bytecode?
+  RefPtr<ScriptFetchOptions> mFetchOptions;
+  const SRIMetadata mIntegrity;
+  const nsCOMPtr<nsIURI> mReferrer;
+  mozilla::Maybe<nsString>
+      mSourceMapURL;  // Holds source map url for loaded scripts
+
+  // Holds script source data for non-inline scripts.
+  mozilla::Maybe<
+      Variant<ScriptTextBuffer<char16_t>, ScriptTextBuffer<Utf8Unit>>>
+      mScriptData;
+
+  // The length of script source text, set when reading completes. This is used
+  // since mScriptData is cleared when the source is passed to the JS engine.
+  size_t mScriptTextLength;
+
+  // Holds the SRI serialized hash and the script bytecode for non-inline
+  // scripts. The data is laid out according to ScriptBytecodeDataLayout
+  // or, if compression is enabled, ScriptBytecodeCompressedDataLayout.
+  mozilla::Vector<uint8_t> mScriptBytecode;
+  uint32_t mBytecodeOffset;  // Offset of the bytecode in mScriptBytecode
+
+  const nsCOMPtr<nsIURI> mURI;
+  nsCOMPtr<nsIPrincipal> mOriginPrincipal;
+
+  // Keep the URI's filename alive during off thread parsing.
+  // Also used by workers to report on errors while loading, and used by
+  // worklets as the file name in compile options.
+  nsAutoCString mURL;
+
+  // The base URL used for resolving relative module imports.
+  nsCOMPtr<nsIURI> mBaseURL;
+
+  // Holds the top-level JSScript that corresponds to the current source, once
+  // it is parsed, and planned to be saved in the bytecode cache.
+  //
+  // NOTE: This field is not used for ModuleLoadRequest.
+  //       See ModuleLoadRequest::mIsMarkedForBytecodeEncoding.
+  JS::Heap<JSScript*> mScriptForBytecodeEncoding;
+
+  // Holds the Cache information, which is used to register the bytecode
+  // on the cache entry, such that we can load it the next time.
+  nsCOMPtr<nsICacheInfoChannel> mCacheInfo;
+
+  // LoadContext for augmenting the load depending on the loading
+  // context (DOM, Worker, etc.)
+  RefPtr<LoadContextBase> mLoadContext;
+};
+
+class ScriptLoadRequestList : private mozilla::LinkedList<ScriptLoadRequest> {
+  using super = mozilla::LinkedList<ScriptLoadRequest>;
+
+ public:
+  ~ScriptLoadRequestList();
+
+  void CancelRequestsAndClear();
+
+#ifdef DEBUG
+  bool Contains(ScriptLoadRequest* aElem) const;
+#endif  // DEBUG
+
+  using super::getFirst;
+  using super::isEmpty;
+
+  void AppendElement(ScriptLoadRequest* aElem) {
+    MOZ_ASSERT(!aElem->isInList());
+    NS_ADDREF(aElem);
+    insertBack(aElem);
+  }
+
+  already_AddRefed<ScriptLoadRequest> Steal(ScriptLoadRequest* aElem) {
+    aElem->removeFrom(*this);
+    return dont_AddRef(aElem);
+  }
+
+  already_AddRefed<ScriptLoadRequest> StealFirst() {
+    MOZ_ASSERT(!isEmpty());
+    return Steal(getFirst());
+  }
+
+  void Remove(ScriptLoadRequest* aElem) {
+    aElem->removeFrom(*this);
+    NS_RELEASE(aElem);
+  }
+};
+
+inline void ImplCycleCollectionUnlink(ScriptLoadRequestList& aField) {
+  while (!aField.isEmpty()) {
+    RefPtr<ScriptLoadRequest> first = aField.StealFirst();
+  }
+}
+
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    ScriptLoadRequestList& aField, const char* aName, uint32_t aFlags) {
+  for (ScriptLoadRequest* request = aField.getFirst(); request;
+       request = request->getNext()) {
+    CycleCollectionNoteChild(aCallback, request, aName, aFlags);
+  }
+}
+
+}  // namespace loader
+}  // namespace JS
+
+#endif  // js_loader_ScriptLoadRequest_h