[VM] Ensure constant table is written in depth-first post-order

The addition of recently added [PartialInstantiationConstant] caused an
issue during constant table writing, becaused we the table writing code
wasn't updated.

This change uses visitChildren to guard against such changes in the
future.

Closes https://github.com/dart-lang/sdk/issues/33095

Change-Id: I3c6b19e1383c6825f11120b2d6255b8b747d0063
Reviewed-on: https://dart-review.googlesource.com/55161
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>

pkg/kernel/lib/binary/ast_to_binary.dart

@@ -2019,59 +2019,32 @@ class ConstantIndexer extends RecursiveVisitor {
 
   ConstantIndexer(this.stringIndexer);
 
-  defaultConstantReference(Constant node) {
-    put(node);
-  }
-
   int put(Constant constant) {
-    final int value = index[constant];
-    if (value != null) return value;
+    final int oldIndex = index[constant];
+    if (oldIndex != null) return oldIndex;
 
     // Traverse DAG in post-order to ensure children have their id's assigned
     // before the parent.
-    return constant.accept(this);
-  }
+    constant.visitChildren(this);
 
-  defaultConstant(Constant node) {
-    final int oldIndex = index[node];
-    if (oldIndex != null) return oldIndex;
-
-    if (node is StringConstant) {
-      stringIndexer.put(node.value);
-    } else if (node is DoubleConstant) {
-      stringIndexer.put('${node.value}');
-    } else if (node is IntConstant) {
-      final int value = node.value;
+    if (constant is StringConstant) {
+      stringIndexer.put(constant.value);
+    } else if (constant is DoubleConstant) {
+      stringIndexer.put('${constant.value}');
+    } else if (constant is IntConstant) {
+      final int value = constant.value;
       if ((value.abs() >> 30) != 0) {
         stringIndexer.put('$value');
       }
     }
 
     final int newIndex = entries.length;
-    entries.add(node);
-    return index[node] = newIndex;
+    entries.add(constant);
+    return index[constant] = newIndex;
   }
 
-  visitMapConstant(MapConstant node) {
-    for (final ConstantMapEntry entry in node.entries) {
-      put(entry.key);
-      put(entry.value);
-    }
-    return defaultConstant(node);
-  }
-
-  visitListConstant(ListConstant node) {
-    for (final Constant entry in node.entries) {
-      put(entry);
-    }
-    return defaultConstant(node);
-  }
-
-  visitInstanceConstant(InstanceConstant node) {
-    for (final Constant entry in node.fieldValues.values) {
-      put(entry);
-    }
-    return defaultConstant(node);
+  defaultConstantReference(Constant node) {
+    put(node);
   }
 
   int operator [](Constant node) => index[node];

tests/language_2/vm/regress_33095_test.dart

@@ -0,0 +1,19 @@
+// Copyright (c) 2018, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import "package:expect/expect.dart";
+
+typedef String IntFunctionType(int _);
+
+class Box {
+  final IntFunctionType fun;
+  const Box(this.fun);
+}
+
+String genericFunction<T>(T v) => '$v';
+
+void main() {
+  const list = const [const Box(genericFunction)];
+  Expect.equals('42', list.first.fun(42));
+}