Add Iterable.fold (and Stream.fold) which replace `reduce`.

sdk/lib/web_sql/dartium/web_sql_dartium.dart

Index: sdk/lib/web_sql/dartium/web_sql_dartium.dart
diff --git a/sdk/lib/web_sql/dartium/web_sql_dartium.dart b/sdk/lib/web_sql/dartium/web_sql_dartium.dart
index 994d25dac8546a2175320d6be89eac97268638af..2fca22d108bc2db86ed41b956e0812b32928ca98 100644
--- a/sdk/lib/web_sql/dartium/web_sql_dartium.dart
+++ b/sdk/lib/web_sql/dartium/web_sql_dartium.dart
@@ -289,6 +289,10 @@ class SqlResultSetRowList extends NativeFieldWrapperClass1 implements List<Map>
     return IterableMixinWorkaround.reduce(this, initialValue, combine);
   }
 
+  dynamic fold(dynamic initialValue, dynamic combine(dynamic, Map)) {
+    return IterableMixinWorkaround.fold(this, initialValue, combine);
+  }
+
   bool contains(Map element) => IterableMixinWorkaround.contains(this, element);
 
   void forEach(void f(Map element)) => IterableMixinWorkaround.forEach(this, f);