Reland "Track field types.".

src/hydrogen-check-elimination.cc

Index: src/hydrogen-check-elimination.cc
diff --git a/src/hydrogen-check-elimination.cc b/src/hydrogen-check-elimination.cc
index 52a549299a24e7913a59aeb656e7e55c87c013fc..4fd769f9241e0186c5158067d82caa84ee1ccd4c 100644
--- a/src/hydrogen-check-elimination.cc
+++ b/src/hydrogen-check-elimination.cc
@@ -382,7 +382,13 @@ class HCheckTable : public ZoneObject {
 
   void ReduceLoadNamedField(HLoadNamedField* instr) {
     // Reduce a load of the map field when it is known to be a constant.
-    if (!IsMapAccess(instr->access())) return;
+    if (!IsMapAccess(instr->access())) {
+      // Check if we introduce a map here.
+      if (!instr->map().IsNull()) {
+        Insert(instr, instr, instr->map());
+      }
+      return;
+    }
 
     HValue* object = instr->object()->ActualValue();
     MapSet maps = FindMaps(object);