Cherry-pick ab6f033. rdar://problem/111986083

    REGRESSION (265825@main): Safari CPU usage in SurferJoannaProxy increased by 5.8%
    https://bugs.webkit.org/show_bug.cgi?id=259805
    rdar://111986083

    Reviewed by Matt Woodrow.

    The fix in 265825@main caused a slight performance regression. We can
    now back out most of it, thanks to a change in CoreAnimation.

    The thing we don't restore is the CATransaction.

    * Source/WebCore/PAL/pal/spi/cocoa/QuartzCoreSPI.h:
    * Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.mm:
    (WebKit::RemoteLayerTreeDrawingAreaProxy::commitLayerTree):

    Canonical link: https://commits.webkit.org/266557@main

Identifier: 265870.303@safari-7616.1.27.10-branch

Source/WebCore/PAL/pal/spi/cocoa/QuartzCoreSPI.h

@@ -193,7 +193,6 @@ typedef enum {
     kCATransactionPhasePreLayout,
     kCATransactionPhasePreCommit,
     kCATransactionPhasePostCommit,
-    kCATransactionPhasePostSynchronize = 5,
     kCATransactionPhaseNull = ~0u
 } CATransactionPhase;
 

Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.mm

@@ -160,25 +160,8 @@
 
 void RemoteLayerTreeDrawingAreaProxy::commitLayerTree(IPC::Connection& connection, const Vector<std::pair<RemoteLayerTreeTransaction, RemoteScrollingCoordinatorTransaction>>& transactions)
 {
-    Vector<MachSendRight> sendRights;
-    for (auto& transaction : transactions) {
-        // commitLayerTreeTransaction consumes the incoming buffers, so we need to grab them first.
-        for (auto& [layerID, properties] : transaction.first.changedLayerProperties()) {
-            const auto backingStoreProperties = properties->backingStoreProperties.get();
-            if (!backingStoreProperties)
-                continue;
-            if (const auto& backendHandle = backingStoreProperties->bufferHandle()) {
-                if (const auto* sendRight = std::get_if<MachSendRight>(&backendHandle.value()))
-                    sendRights.append(*sendRight);
-            }
-        }
-
+    for (auto& transaction : transactions)
         commitLayerTreeTransaction(connection, transaction.first, transaction.second);
-    }
-
-    // Keep IOSurface send rights alive until the commit makes it to the render server, otherwise we will
-    // prematurely drop the only reference to them, and `inUse` will be wrong for a brief window.
-    [CATransaction addCommitHandler:[sendRights = WTFMove(sendRights)]() { } forPhase:kCATransactionPhasePostSynchronize];
 }
 
 void RemoteLayerTreeDrawingAreaProxy::commitLayerTreeTransaction(IPC::Connection& connection, const RemoteLayerTreeTransaction& layerTreeTransaction, const RemoteScrollingCoordinatorTransaction& scrollingTreeTransaction)