Make print interceptable.

sdk/lib/_internal/lib/collection_dev_patch.dart

Index: sdk/lib/_internal/lib/collection_dev_patch.dart
diff --git a/sdk/lib/_internal/lib/collection_dev_patch.dart b/sdk/lib/_internal/lib/collection_dev_patch.dart
index f224f24aab6db81fdd02fe889ed215cbb223c6e5..f37f71390b156bf8c21bb899f83d981f54f82836 100644
--- a/sdk/lib/_internal/lib/collection_dev_patch.dart
+++ b/sdk/lib/_internal/lib/collection_dev_patch.dart
@@ -2,7 +2,13 @@
 // 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 'dart:_js_helper' show Primitives;
+
 patch class Symbol implements core.Symbol {
   patch const Symbol(String name)
       : this._name = name;
 }
+
+patch void internalPrint(Object object) {
+  Primitives.printString(object.toString());
+}