Eliminate redundant smi checks

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 1d1f94bd0e82ffa58301ce91b772a9a86d28dc2b..b4f747a7aa76f5bc85a82588e3260c10f19d8401 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5482,7 +5482,8 @@ HInstruction* HGraphBuilder::BuildFastElementAccess(HValue* elements,
   if (IsFastDoubleElementsKind(elements_kind)) {
     return new(zone()) HLoadKeyedFastDoubleElement(elements, checked_key, mode);
   } else {  // Smi or Object elements.
-    return new(zone()) HLoadKeyedFastElement(elements, checked_key, mode);
+    return new(zone()) HLoadKeyedFastElement(elements, checked_key,
+                                             mode, elements_kind);
   }
 }
 
@@ -5530,7 +5531,7 @@ HInstruction* HGraphBuilder::BuildMonomorphicElementAccess(HValue* object,
          fast_elements ||
          map->has_fast_double_elements());
   if (map->instance_type() == JS_ARRAY_TYPE) {
-    length = AddInstruction(new(zone()) HJSArrayLength(object, mapcheck));
+    length = AddInstruction(new(zone()) HJSArrayLength(object, mapcheck, true));
   } else {
     length = AddInstruction(new(zone()) HFixedArrayBaseLength(elements));
   }
@@ -5685,7 +5686,8 @@ HValue* HGraphBuilder::HandlePolymorphicElementAccess(HValue* object,
 
         set_current_block(if_jsarray);
         HInstruction* length;
-        length = AddInstruction(new(zone()) HJSArrayLength(object, typecheck));
+        length =
+            AddInstruction(new(zone()) HJSArrayLength(object, typecheck, true));
         checked_key = AddInstruction(new(zone()) HBoundsCheck(key, length));
         access = AddInstruction(BuildFastElementAccess(
             elements, checked_key, val, elements_kind, is_store));
@@ -5884,8 +5886,7 @@ void HGraphBuilder::VisitProperty(Property* expr) {
     AddInstruction(new(zone()) HCheckNonSmi(array));
     HInstruction* mapcheck =
         AddInstruction(HCheckInstanceType::NewIsJSArray(array, zone()));
-    instr = new(zone()) HJSArrayLength(array, mapcheck);
-
+    instr = new(zone()) HJSArrayLength(array, mapcheck, false);
   } else if (expr->IsStringLength()) {
     HValue* string = Pop();
     AddInstruction(new(zone()) HCheckNonSmi(string));