--- a/layout/style/StyleSheet.cpp
+++ b/layout/style/StyleSheet.cpp
@@ -6,16 +6,18 @@
 
 #include "mozilla/StyleSheet.h"
 
 #include "mozilla/dom/ShadowRoot.h"
 #include "mozilla/ServoStyleSheet.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/CSSStyleSheet.h"
 
+#include "nsNullPrincipal.h"
+
 namespace mozilla {
 
 StyleSheet::StyleSheet(StyleBackendType aType, css::SheetParsingMode aParsingMode)
   : mDocument(nullptr)
   , mOwningNode(nullptr)
   , mParsingMode(aParsingMode)
   , mType(aType)
   , mDisabled(false)
@@ -71,9 +73,26 @@ StyleSheet::SetComplete()
   if (mOwningNode && !mDisabled &&
       mOwningNode->HasFlag(NODE_IS_IN_SHADOW_TREE) &&
       mOwningNode->IsContent()) {
     dom::ShadowRoot* shadowRoot = mOwningNode->AsContent()->GetContainingShadow();
     shadowRoot->StyleSheetChanged();
   }
 }
 
+StyleSheetInfo::StyleSheetInfo(CORSMode aCORSMode,
+                               ReferrerPolicy aReferrerPolicy,
+                               const dom::SRIMetadata& aIntegrity)
+  : mPrincipal(nsNullPrincipal::Create())
+  , mCORSMode(aCORSMode)
+  , mReferrerPolicy(aReferrerPolicy)
+  , mIntegrity(aIntegrity)
+  , mComplete(false)
+#ifdef DEBUG
+  , mPrincipalSet(false)
+#endif
+{
+  if (!mPrincipal) {
+    NS_RUNTIMEABORT("nsNullPrincipal::Init failed");
+  }
+}
+
 } // namespace mozilla

deleted file mode 100644
--- a/layout/style/StyleSheetInfo.cpp
+++ /dev/null
@@ -1,48 +0,0 @@
-/* -*- 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/. */
-
-#include "StyleSheetInfo.h"
-
-#include "nsIURI.h"
-#include "nsNullPrincipal.h"
-
-namespace mozilla {
-
-using namespace mozilla::dom;
-
-StyleSheetInfo::StyleSheetInfo(CORSMode aCORSMode,
-                               ReferrerPolicy aReferrerPolicy,
-                               const SRIMetadata& aIntegrity)
-  : mPrincipal(nsNullPrincipal::Create())
-  , mCORSMode(aCORSMode)
-  , mReferrerPolicy(aReferrerPolicy)
-  , mIntegrity(aIntegrity)
-  , mComplete(false)
-#ifdef DEBUG
-  , mPrincipalSet(false)
-#endif
-{
-  if (!mPrincipal) {
-    NS_RUNTIMEABORT("nsNullPrincipal::Init failed");
-  }
-}
-
-StyleSheetInfo::StyleSheetInfo(const StyleSheetInfo& aCopy)
-  : mSheetURI(aCopy.mSheetURI)
-  , mOriginalSheetURI(aCopy.mOriginalSheetURI)
-  , mBaseURI(aCopy.mBaseURI)
-  , mPrincipal(aCopy.mPrincipal)
-  , mCORSMode(aCopy.mCORSMode)
-  , mReferrerPolicy(aCopy.mReferrerPolicy)
-  , mIntegrity(aCopy.mIntegrity)
-  , mComplete(aCopy.mComplete)
-#ifdef DEBUG
-  , mPrincipalSet(aCopy.mPrincipalSet)
-#endif
-{
-}
-
-} // namespace mozilla

--- a/layout/style/StyleSheetInfo.h
+++ b/layout/style/StyleSheetInfo.h
@@ -26,17 +26,16 @@ namespace mozilla {
  */
 struct StyleSheetInfo
 {
   typedef net::ReferrerPolicy ReferrerPolicy;
 
   StyleSheetInfo(CORSMode aCORSMode,
                  ReferrerPolicy aReferrerPolicy,
                  const dom::SRIMetadata& aIntegrity);
-  StyleSheetInfo(const StyleSheetInfo& aCopy);
 
   nsCOMPtr<nsIURI>       mSheetURI; // for error reports, etc.
   nsCOMPtr<nsIURI>       mOriginalSheetURI;  // for GetHref.  Can be null.
   nsCOMPtr<nsIURI>       mBaseURI; // for resolving relative URIs
   nsCOMPtr<nsIPrincipal> mPrincipal;
   CORSMode               mCORSMode;
   // The Referrer Policy of a stylesheet is used for its child sheets, so it is
   // stored here.

--- a/layout/style/moz.build
+++ b/layout/style/moz.build
@@ -193,17 +193,16 @@ UNIFIED_SOURCES += [
     'RuleProcessorCache.cpp',
     'ServoBindings.cpp',
     'ServoElementSnapshot.cpp',
     'ServoStyleSet.cpp',
     'ServoStyleSheet.cpp',
     'StyleAnimationValue.cpp',
     'StyleRule.cpp',
     'StyleSheet.cpp',
-    'StyleSheetInfo.cpp',
     'SVGAttrAnimationRuleProcessor.cpp',
 ]
 
 # nsCSSRuleProcessor.cpp needs to be built separately because it uses plarena.h.
 # nsLayoutStylesheetCache.cpp needs to be built separately because it uses
 # nsExceptionHandler.h, which includes windows.h.
 SOURCES += [
     'nsCSSRuleProcessor.cpp',