Add more safe points in compiler

runtime/vm/scavenger.h

Index: runtime/vm/scavenger.h
diff --git a/runtime/vm/scavenger.h b/runtime/vm/scavenger.h
index 9bffb215b806dac03928c360b5f1712b9532d839..e5b8dd77f40c4d8383ad4b13bff544784d90657d 100644
--- a/runtime/vm/scavenger.h
+++ b/runtime/vm/scavenger.h
@@ -198,10 +198,11 @@ class Scavenger {
   // Ids for time and data records in Heap::GCStats.
   enum {
     // Time
-    kVisitIsolateRoots = 0,
-    kIterateStoreBuffers = 1,
-    kProcessToSpace = 2,
-    kIterateWeaks = 3,
+    kSafePoint = 0,
+    kVisitIsolateRoots = 1,
+    kIterateStoreBuffers = 2,
+    kProcessToSpace = 3,
+    kIterateWeaks = 4,
     // Data
     kStoreBufferEntries = 0,
     kDataUnused1 = 1,