Fastpath some spread-call desugaring.

src/lookup.cc

Index: src/lookup.cc
diff --git a/src/lookup.cc b/src/lookup.cc
index 256aa02d21cf4ffffc9487b0b2bbd6662bb07cb6..17459bf208ca5ca9025701904d1b0eaa8e662b40 100644
--- a/src/lookup.cc
+++ b/src/lookup.cc
@@ -194,6 +194,11 @@ void LookupIterator::InternalUpdateProtector() {
   } else if (*name_ == heap()->has_instance_symbol()) {
     if (!isolate_->IsHasInstanceLookupChainIntact()) return;
     isolate_->InvalidateHasInstanceProtector();
+  } else if (*name_ == heap()->iterator_symbol()) {
+    if (!isolate_->IsArrayIteratorLookupChainIntact()) return;
+    if (holder_->IsJSArray()) {
+      isolate_->InvalidateArrayIteratorProtector();
+    }

[caitp, 2016/11/11 16:19:17]

this is a very different case from the version in my CL. We will need to rename
one of them. The ArrayIterator inlining should not be broken by this.

   }
 }