Avoid one repeated property lookup when computing load ICs.

src/lookup.h

Index: src/lookup.h
diff --git a/src/lookup.h b/src/lookup.h
index c96b2d11dd640d7044b635a29fcb4325f5ae672a..009f7c9b52e6373e9664afaee593dd243c1f37fa 100644
--- a/src/lookup.h
+++ b/src/lookup.h
@@ -131,11 +131,25 @@ class LookupIterator V8_FINAL BASE_EMBEDDED {
     ASSERT(has_property_);
     return property_details_;
   }
+  bool has_fast_properties() const { return !holder_map_->is_dictionary_map(); }
   int descriptor_number() const {
     ASSERT(has_property_);
     ASSERT_EQ(DESCRIPTOR, property_encoding_);
     return number_;
   }
+  int dictionary_entry() const {
+    ASSERT(has_property_);
+    ASSERT_EQ(DICTIONARY, property_encoding_);
+    return number_;
+  }
+  bool IsConfigurable() const { return !property_details().IsDontDelete(); }
+  Representation representation() const {
+    return property_details().representation();
+  }
+  FieldIndex GetFieldIndex() const {
+    ASSERT_EQ(PROPERTY, state_);
+    return FieldIndex::ForLookupIterator(this);
+  }
   Handle<Object> GetAccessors() const;
   Handle<Object> GetDataValue() const;
   void WriteDataValue(Handle<Object> value);