Ensure objects emitted in code are allocated in old space.

runtime/vm/ast.h

Index: runtime/vm/ast.h
diff --git a/runtime/vm/ast.h b/runtime/vm/ast.h
index b02a10d9c5bb9d4f1474dcb78a4c4c3fc3fa2f10..ce4e064d638de4ee05676209f481053383958cde 100644
--- a/runtime/vm/ast.h
+++ b/runtime/vm/ast.h
@@ -309,6 +309,7 @@ class LiteralNode : public AstNode {
   LiteralNode(intptr_t token_pos, const Instance& literal)
       : AstNode(token_pos), literal_(literal) {
     ASSERT(literal.IsZoneHandle());
+    ASSERT(literal.IsSmi() || literal.IsOld());
 #if defined(DEBUG)
     if (literal.IsString()) {
       ASSERT(String::Cast(literal).IsSymbol());