Implement removeRange, and update some documentation on the list interface.

tests/corelib/src/ConstListRemoveRangeTest.dart

Index: tests/corelib/src/ConstListRemoveRangeTest.dart
===================================================================
--- tests/corelib/src/ConstListRemoveRangeTest.dart	(revision 394)
+++ tests/corelib/src/ConstListRemoveRangeTest.dart	(working copy)
@@ -13,15 +13,7 @@
 }
 
 testImmutable(var list) {
-  expectUOE(() { list.setRange(0, 0, const []); });
-  expectUOE(() { list.setRange(0, 1, const [], 1); });
-  expectUOE(() { list.setRange(0, 1, const []); });
-  expectUOE(() { list.setRange(0, 0, []); });
-  expectUOE(() { list.setRange(0, 1, [], 1); });
-  expectUOE(() { list.setRange(0, 1, []); });
-  expectUOE(() { list.setRange(0, 0, const [1]); });
-  expectUOE(() { list.setRange(0, 1, const [1]); });
-  expectUOE(() { list.setRange(0, 0, [1]); });
-  expectUOE(() { list.setRange(0, 1, [1]); });
-  expectUOE(() { list.setRange(0, 1, [1], 1); });
+  expectUOE(() { list.removeRange(0, 0); });
+  expectUOE(() { list.removeRange(0, 1); });
+  expectUOE(() { list.removeRange(-1, 1); });
 }