Add Smi::Zero and replace all Smi::FromInt(0) calls

src/layout-descriptor-inl.h

Index: src/layout-descriptor-inl.h
diff --git a/src/layout-descriptor-inl.h b/src/layout-descriptor-inl.h
index 3f150658e7f6628a517b7708113d5cc9162cff4c..bade05e2e8517db654c0adafda7b84eec798c9af 100644
--- a/src/layout-descriptor-inl.h
+++ b/src/layout-descriptor-inl.h
@@ -18,7 +18,7 @@ LayoutDescriptor* LayoutDescriptor::FromSmi(Smi* smi) {
 Handle<LayoutDescriptor> LayoutDescriptor::New(Isolate* isolate, int length) {
   if (length <= kSmiValueSize) {
     // The whole bit vector fits into a smi.
-    return handle(LayoutDescriptor::FromSmi(Smi::FromInt(0)), isolate);
+    return handle(LayoutDescriptor::FromSmi(Smi::kZero), isolate);
   }
   length = GetSlowModeBackingStoreLength(length);
   return Handle<LayoutDescriptor>::cast(isolate->factory()->NewFixedTypedArray(
@@ -37,7 +37,7 @@ bool LayoutDescriptor::InobjectUnboxedField(int inobject_properties,
 
 
 LayoutDescriptor* LayoutDescriptor::FastPointerLayout() {
-  return LayoutDescriptor::FromSmi(Smi::FromInt(0));
+  return LayoutDescriptor::FromSmi(Smi::kZero);
 }