Fix field type handling in load elimination.

src/hydrogen-load-elimination.cc

Index: src/hydrogen-load-elimination.cc
diff --git a/src/hydrogen-load-elimination.cc b/src/hydrogen-load-elimination.cc
index f84eac046b5d88297ba9d75eda72c57e356037af..094793473aeacb7ac4f25a981194f836780a3091 100644
--- a/src/hydrogen-load-elimination.cc
+++ b/src/hydrogen-load-elimination.cc
@@ -78,7 +78,10 @@ class HLoadEliminationTable : public ZoneObject {
         HValue* result = load(l);
         if (result != instr &&
             result->type().Equals(instr->type()) &&
-            result->representation().Equals(instr->representation())) {
+            result->representation().Equals(instr->representation()) &&
+            (!result->IsLoadNamedField() ||
+             HLoadNamedField::cast(instr)->map_set()->IsSubset(
+                 HLoadNamedField::cast(result)->map_set()))) {
           // The load can be replaced with a previous load or a value.
           TRACE(("  replace L%d -> v%d\n", instr->id(), result->id()));
           instr->DeleteAndReplaceWith(result);