Push heap stats as HeapStatsUpdate struct instead of raw array of uint32_t values.

src/profile-generator.h

Index: src/profile-generator.h
diff --git a/src/profile-generator.h b/src/profile-generator.h
index 897962e8c6162db20f44bb8f5052a833992dd853..1d2969bc21bbd031759d8c26aef9ef20547e8e2d 100644
--- a/src/profile-generator.h
+++ b/src/profile-generator.h
@@ -741,7 +741,7 @@ class HeapObjectsMap {
   struct TimeInterval {
     explicit TimeInterval(SnapshotObjectId id) : id(id), size(0), count(0) { }
     SnapshotObjectId id;
-    unsigned int size;
+    uint32_t size;
     uint32_t count;
   };