Remove some dead ZoneList typedefs.

src/ast/ast.h

Index: src/ast/ast.h
diff --git a/src/ast/ast.h b/src/ast/ast.h
index 9acea70985af2e880704f6846fea83be2c6e3a07..0ed089f155e0e2980e5c05c60605c60d574d2bcc 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -126,11 +126,6 @@ AST_NODE_LIST(DEF_FORWARD_DECLARATION)
 #undef DEF_FORWARD_DECLARATION
 
 
-// Typedef only introduced to avoid unreadable code.
-typedef ZoneList<Handle<String>> ZoneStringList;
-typedef ZoneList<Handle<Object>> ZoneObjectList;
-
-
 class FeedbackVectorSlotCache {
  public:
   explicit FeedbackVectorSlotCache(Zone* zone)