Bug 1626570 - Improve handling of copying arrays in dom/html/. r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D73647

dom/html/HTMLInputElement.cpp

@@ -6803,8 +6803,7 @@ void HTMLInputElement::SetFilePickerFiltersFromAccept(
 
   // Remove similar filters
   // Iterate over a copy, as we might modify the original filters list
-  nsTArray<nsFilePickerFilter> filtersCopy;
-  filtersCopy = filters;
+  const nsTArray<nsFilePickerFilter> filtersCopy = filters.Clone();
   for (uint32_t i = 0; i < filtersCopy.Length(); ++i) {
     const nsFilePickerFilter& filterToCheck = filtersCopy[i];
     if (filterToCheck.mFilterMask) {

dom/html/HTMLMediaElement.cpp

@@ -741,7 +741,7 @@ class HTMLMediaElement::MediaStreamRenderer
         mWatchManager(this, aMainThread) {}
 
   void Shutdown() {
-    for (const auto& t : nsTArray<WeakPtr<MediaStreamTrack>>(mAudioTracks)) {
+    for (const auto& t : mAudioTracks.Clone()) {
       if (t) {
         RemoveTrack(t->AsAudioStreamTrack());
       }
@@ -3691,10 +3691,10 @@ already_AddRefed<DOMMediaStream> HTMLMediaElement::CaptureStreamInternal(
   }
 
   nsPIDOMWindowInner* window = OwnerDoc()->GetInnerWindow();
-  OutputMediaStream* out = mOutputStreams.AppendElement(OutputMediaStream(
+  OutputMediaStream* out = mOutputStreams.EmplaceBack(
       MakeRefPtr<DOMMediaStream>(window),
       aStreamCaptureType == StreamCaptureType::CAPTURE_AUDIO,
-      aFinishBehavior == StreamCaptureBehavior::FINISH_WHEN_ENDED));
+      aFinishBehavior == StreamCaptureBehavior::FINISH_WHEN_ENDED);
 
   if (aFinishBehavior == StreamCaptureBehavior::FINISH_WHEN_ENDED &&
       !mOutputTrackSources.IsEmpty()) {

dom/html/HTMLSlotElement.cpp

@@ -137,7 +137,7 @@ void HTMLSlotElement::AssignedNodes(const AssignedNodesOptions& aOptions,
     return FlattenAssignedNodes(this, aNodes);
   }
 
-  aNodes = mAssignedNodes;
+  aNodes = mAssignedNodes.Clone();
 }
 
 void HTMLSlotElement::AssignedElements(const AssignedNodesOptions& aOptions,