Add List.unmodifiable constructor.

sdk/lib/internal/list.dart

Index: sdk/lib/internal/list.dart
diff --git a/sdk/lib/internal/list.dart b/sdk/lib/internal/list.dart
index 6b94c6cbbf9197b3a135d78eedbbe90ae15fa1c0..8fe02c4736e75334939e0ba7844735bd1961157d 100644
--- a/sdk/lib/internal/list.dart
+++ b/sdk/lib/internal/list.dart
@@ -374,3 +374,19 @@ abstract class NonGrowableListError {
  * state.
  */
 external List makeListFixedLength(List growableList);
+
+/**
+ * Converts a fixed-length list to an unmodifiable list.
+ *
+ * For internal use only.
+ * Only works for core fixed-length lists as created by `new List(length)`,
+ * or as returned by [makeListFixedLength].
+ *
+ * The operation is efficient. It doesn't copy the elements, but converts
+ * the existing list directly to a fixed length list.
+ * That means that it is a destructive conversion.
+ * The original list should not be used afterwards.
+ *
+ * The unmodifialbe list type is similar to the one used by const lists.

[sra1, 2015/04/22 21:17:31]

spelling

+ */
+external List makeFixedListUnmodifiable(List fixedLengthList);