Add list.removeAt method.

tests/corelib/list_removeat_test.dart

+// Copyright (c) 2011, 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.
+
+void main() {
+  // Normal modifiable list.
+  var l1 = [0, 1, 2, 3, 4];
+
+  // Index must be integer and in range.
+  Expect.throws(() { l1.removeAt(-1); },
+                (e) => e is IndexOutOfRangeException,
+                "negative");
+  Expect.throws(() { l1.removeAt(5); },
+                (e) => e is IndexOutOfRangeException,
+                "too large");
+  Expect.throws(() { l1.removeAt("1"); },
+                (e) => e is IllegalArgumentException,
+                "string");
+  Expect.throws(() { l1.removeAt(1.5); },
+                (e) => e is IllegalArgumentException,
+                "double");
+
+  Expect.equals(2, l1.removeAt(2), "l1-remove2");
+  Expect.equals(1, l1[1], "l1-1[1]");
+
+  Expect.equals(3, l1[2], "l1-1[2]");
+  Expect.equals(4, l1[3], "l1-1[3]");
+  Expect.equals(4, l1.length, "length-1");
+
+  Expect.equals(0, l1.removeAt(0), "l1-remove0");
+  Expect.equals(1, l1[0], "l1-2[0]");
+  Expect.equals(3, l1[1], "l1-2[1]");
+  Expect.equals(4, l1[2], "l1-2[2]");
+  Expect.equals(3, l1.length, "length-2");
+
+  // Fixed size list.
+  var l2 = new List(5);
+  for (var i = 0; i < 5; i++) l2[i] = i;
+  Expect.throws(() { l2.removeAt(2); },
+                (e) => e is UnsupportedOperationException,
+                "fixed-length");
+
+  // Unmodifiable list.
+  var l3 = const [0, 1, 2, 3, 4];
+  Expect.throws(() { l3.removeAt(2); },
+                (e) => e is UnsupportedOperationException,
+                "unmodifiable");
+
+  // Empty list is not special.
+  var l4 = [];
+  Expect.throws(() { l4.removeAt(0); },
+                (e) => e is IndexOutOfRangeException,
+                "empty");
+}