Rename IsDontDelete to IsConfigurable (and invert conditions)

src/lookup.h

Index: src/lookup.h
diff --git a/src/lookup.h b/src/lookup.h
index 5e2b4921801c87926727323b50b3a4070c0eadf8..e09eeeea244e74b18c81a80d01db51c3eb3300a7 100644
--- a/src/lookup.h
+++ b/src/lookup.h
@@ -153,7 +153,7 @@ class LookupIterator V8_FINAL BASE_EMBEDDED {
     DCHECK(has_property_);
     return property_details_;
   }
-  bool IsConfigurable() const { return !property_details().IsDontDelete(); }
+  bool IsConfigurable() const { return property_details().IsConfigurable(); }
   bool IsReadOnly() const { return property_details().IsReadOnly(); }
   Representation representation() const {
     return property_details().representation();