macOS: trailing closures for FlutterRunLoop.perform* (#168415)

Support trailing closure syntax in FlutterRunLoop perform methods. This
allows us to write Swift code like:

```
FlutterRunLoop.mainLoop.perform(withDelay: delay) {
  // code.
}
```

This also matches the ordering used in NSRunLoop/RunLoop:
*
https://developer.apple.com/documentation/foundation/runloop/perform(inmodes:block:)?language=objc
*
https://developer.apple.com/documentation/foundation/runloop/perform(inmodes:block:)

Follow-up to flutter/flutter#168174.

No tests since this is just a method rename.

Issue: https://github.com/flutter/flutter/issues/144791

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we expect every widget to implement].
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- [X] I listed at least one issue that this PR fixes in the description
above.
- [X] I updated/added relevant documentation (doc comments with `///`).
- [X] I added new tests to check the change I am making, or this PR is
[test-exempt].
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Fixes] where supported.
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engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterEngine.mm

@@ -1565,16 +1565,16 @@ static void SetThreadPriority(FlutterThreadPriority priority) {
 
   const auto engine_time = _embedderAPI.GetCurrentTime();
   [FlutterRunLoop.mainRunLoop
-      performBlock:^{
-        FlutterEngine* self = weakSelf;
-        if (self != nil && self->_engine != nil) {
-          auto result = _embedderAPI.RunTask(self->_engine, &task);
-          if (result != kSuccess) {
-            NSLog(@"Could not post a task to the Flutter engine.");
-          }
-        }
-      }
-        afterDelay:(targetTime - (double)engine_time) / NSEC_PER_SEC];
+      performAfterDelay:(targetTime - (double)engine_time) / NSEC_PER_SEC
+                  block:^{
+                    FlutterEngine* self = weakSelf;
+                    if (self != nil && self->_engine != nil) {
+                      auto result = _embedderAPI.RunTask(self->_engine, &task);
+                      if (result != kSuccess) {
+                        NSLog(@"Could not post a task to the Flutter engine.");
+                      }
+                    }
+                  }];
 }
 
 // Getter used by test harness, only exposed through the FlutterEngine(Test) category

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterResizeSynchronizer.mm

@@ -45,13 +45,12 @@
   if (_inResize) {
     delay = 0;
   }
-  [FlutterRunLoop.mainRunLoop
-      performBlock:^{
-        _didReceiveFrame = YES;
-        _contentSize = size;
-        notify();
-      }
-        afterDelay:delay];
+  [FlutterRunLoop.mainRunLoop performAfterDelay:delay
+                                          block:^{
+                                            _didReceiveFrame = YES;
+                                            _contentSize = size;
+                                            notify();
+                                          }];
 }
 
 - (void)shutDown {

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterRunLoop.swift

@@ -107,8 +107,7 @@ import Foundation
   }
 
   // Schedules a block to be executed on the main thread.
-  @objc(performBlock:afterDelay:)
-  public func perform(block: @escaping () -> Void, afterDelay delay: TimeInterval) {
+  @objc public func perform(afterDelay delay: TimeInterval, block: @escaping () -> Void) {
     tasksLock.lock()
     defer { tasksLock.unlock() }
 
@@ -123,8 +122,8 @@ import Foundation
 
   // Schedules a block to be executed on the main thread after a delay.
   @objc(performBlock:)
-  public func perform(block: @escaping () -> Void) {
-    perform(block: block, afterDelay: 0)
+  public func perform(_ block: @escaping () -> Void) {
+    perform(afterDelay: 0, block: block)
   }
 
   private func performExpiredTasks() {

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterVSyncWaiter.mm

@@ -78,17 +78,17 @@ static const CFTimeInterval kTimerLatencyCompensation = 0.001;
     TRACE_VSYNC("DisplayLinkCallback-Original", _pendingBaton.value_or(0));
 
     [FlutterRunLoop.mainRunLoop
-        performBlock:^{
-          if (!_pendingBaton.has_value()) {
-            TRACE_VSYNC("DisplayLinkPaused", size_t(0));
-            _displayLink.paused = YES;
-            return;
-          }
-          TRACE_VSYNC("DisplayLinkCallback-Delayed", _pendingBaton.value_or(0));
-          _block(minStart, targetTimestamp, *_pendingBaton);
-          _pendingBaton = std::nullopt;
-        }
-          afterDelay:remaining];
+        performAfterDelay:remaining
+                    block:^{
+                      if (!_pendingBaton.has_value()) {
+                        TRACE_VSYNC("DisplayLinkPaused", size_t(0));
+                        _displayLink.paused = YES;
+                        return;
+                      }
+                      TRACE_VSYNC("DisplayLinkCallback-Delayed", _pendingBaton.value_or(0));
+                      _block(minStart, targetTimestamp, *_pendingBaton);
+                      _pendingBaton = std::nullopt;
+                    }];
   }
 }
 
@@ -138,13 +138,12 @@ static const CFTimeInterval kTimerLatencyCompensation = 0.001;
       delay = std::max(start - now - kTimerLatencyCompensation, 0.0);
     }
 
-    [FlutterRunLoop.mainRunLoop
-        performBlock:^{
-          CFTimeInterval targetTimestamp = start + tick_interval;
-          TRACE_VSYNC("SynthesizedInitialVSync", baton);
-          _block(start, targetTimestamp, baton);
-        }
-          afterDelay:delay];
+    [FlutterRunLoop.mainRunLoop performAfterDelay:delay
+                                            block:^{
+                                              CFTimeInterval targetTime = start + tick_interval;
+                                              TRACE_VSYNC("SynthesizedInitialVSync", baton);
+                                              _block(start, targetTime, baton);
+                                            }];
     _displayLink.paused = NO;
   } else {
     _pendingBaton = baton;