--- 
+++ 
@@ -19,6 +19,9 @@
 
           // Deleting a property has different semantics from deleting
           // a variable, so deleted properties should not be inlined.
+ if (gramps.getType() == Token.DELPROP) {
+            return false;
+          }
 
           // NOTE(nicksantos): This pass's object-splitting algorithm has
           // a blind spot. It assumes that if a property isn't defined on an