Implement Direct3D semaphores

Change-Id: Iadfa14965bbe11cfea556ade5d46e264f0ace61a
Bug: skia:9935
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/298752
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/RELEASE_NOTES.txt b/RELEASE_NOTES.txt
index 0773702..81e91ec 100644
--- a/RELEASE_NOTES.txt
+++ b/RELEASE_NOTES.txt
@@ -4,6 +4,13 @@
 
 * * *
 
+Milestone 86
+------------
+  * Enable BackendSemaphores for the Direct3D backend.
+    https://review.skia.org/298752
+
+* * *
+
 Milestone 85
 ------------