What

Adds a CADisplayLink-backed AnimationFrame module exposing two frame-callback surfaces on every global (workers included):

• requestAnimationFrame(fn) / cancelAnimationFrame(handle) — spec semantics: every request registers its own one-shot entry and returns a numeric handle; cancellation is by handle (and can only touch rAF entries); fn receives a single DOMHighResTimeStamp on the isolate's performance timeline.
• __postFrameCallback(fn[, delayMillis]) / __removeFrameCallback(fn) — the Android runtime's compatibility contract (NativeScript/android@d1fc925f): one-shot, deduped by function identity via a _postFrameCallbackId private value (re-posting a pending callback is a no-op), fn(frameTimeNanos, performanceMillis), TypeError on non-function arguments, and delayed entries firing on the first frame after the delay elapses.

How

• One CADisplayLink per isolate, created paused during isolate init on the home thread and attached to that thread's runloop in the common modes (same modes as the EventLoop's timers, so ticks keep arriving during scroll tracking). Posting unpauses it; an empty registry pauses it again, so an idle isolate never wakes per frame.
• CADisplayLink.timestamp shares the mach_absolute_time base with the V8 platform clock, so the vsync instant maps onto the performance timeline through Runtime::TimeOriginMonotonicSeconds() — callbacks observe the frame time, not dispatch time, and every callback in a batch sees the same timestamps.
• Each tick dispatches only entries scheduled before it, so a callback that re-posts runs next frame, never twice in one batch. Callbacks are held by strong persistents until fired or removed, then released (covered by GC tests).
• State is per-isolate and home-thread-only (registered through Caches::registerCacheBoundObject, torn down before Isolate::Dispose like TimerState), so unlike the Android implementation's process-global map, no locking is needed.
• Links QuartzCore into the NativeScript target (it autolinks nothing, and UIKit alone does not resolve CADisplayLink under explicit -framework linking).

Tests

TestRunner/app/tests/AnimationFrameTests.js ports the Android testPostFrameCallback.js suite (existence, argument TypeErrors, single-fire, dedup on double-post, cancel/cancel-then-repost, self-reschedule, GC retention/release) and adds rAF specs (handle + single timestamp arg, once-per-request for the same function, targeted cancellation, batch timestamp equality, frame chaining, dedupe isolation from __postFrameCallback), a delay spec, and a frame-time/performance-timestamp spec. Full suite green locally on the iOS simulator.

Summary by CodeRabbit

• New Features

  • Added support for standard requestAnimationFrame and cancelAnimationFrame APIs on iOS.
  • Added compatibility support for __postFrameCallback and __removeFrameCallback.
  • Improved animation-frame scheduling with cancellation, delays, batching, timestamps, and chained frames.

• Tests

  • Added comprehensive coverage for animation-frame behavior, timing, validation, cancellation, and API interoperability.