Expose transferable constructor to Int8List

runtime/vm/os.h

Index: runtime/vm/os.h
diff --git a/runtime/vm/os.h b/runtime/vm/os.h
index e33b274f7122fd2ec583676464fc8dcba59b8368..7c699c1d82d1840345aaf3d2c06e183d82fc65cd 100644
--- a/runtime/vm/os.h
+++ b/runtime/vm/os.h
@@ -40,6 +40,13 @@ class OS {
   // from midnight January 1, 1970 UTC.
   static int64_t GetCurrentTimeMicros();
 
+  // Returns an aligned pointer in the C heap with room for size bytes.
+  // Alignment must be >= 16 and a power of two.
+  static void* AlignedAllocate(intptr_t size, intptr_t alignment);
+
+  // Frees a pointer returned from AlignedAllocate.
+  static void AlignedFree(void* ptr);
+
   // Returns the activation frame alignment constraint or zero if
   // the platform doesn't care. Guaranteed to be a power of two.
   static word ActivationFrameAlignment();