In GrowMode, force the value to the right representation to avoid deopts between storing the length…

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index d653ff501747467330d325f6630a9416fafe5e75..4eb81414592353bf3ac9e793b985269299594c49 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -2479,6 +2479,9 @@ HInstruction* HGraphBuilder::BuildUncheckedMonomorphicElementAccess(
 
   if (IsGrowStoreMode(store_mode)) {
     NoObservableSideEffectsScope no_effects(this);
+    Representation representation = HStoreKeyed::RequiredValueRepresentation(
+        elements_kind, STORE_TO_INITIALIZED_ENTRY);
+    val = AddUncasted<HForceRepresentation>(val, representation);
     elements = BuildCheckForCapacityGrow(checked_object, elements,
                                          elements_kind, length, key,
                                          is_js_array, access_type);
@@ -2675,9 +2678,7 @@ HInstruction* HGraphBuilder::AddElementAccess(
       val = Add<HClampToUint8>(val);
     }
     return Add<HStoreKeyed>(elements, checked_key, val, elements_kind,
-                            elements_kind == FAST_SMI_ELEMENTS
-                              ? STORE_TO_INITIALIZED_ENTRY
-                              : INITIALIZING_STORE);
+                            STORE_TO_INITIALIZED_ENTRY);
   }
 
   ASSERT(access_type == LOAD);