Refactor List.setRange function.

runtime/lib/typeddata.dart

Index: runtime/lib/typeddata.dart
diff --git a/runtime/lib/typeddata.dart b/runtime/lib/typeddata.dart
index 8bf7a8cf7e2751834ab86947f7a0a5b10ec85be1..ebe0798ccc560b802b2f4ebb2e8b1734012c2e60 100644
--- a/runtime/lib/typeddata.dart
+++ b/runtime/lib/typeddata.dart
@@ -487,10 +487,10 @@ abstract class _TypedListBase {
     return IterableMixinWorkaround.getRangeList(this, start, end);
   }
 
-  void setRange(int start, int length, List from, [int startFrom = 0]) {
-    if (!_setRange(start, length, from, startFrom)) {
+  void setRange(int start, int end, List from, [int startFrom = 0]) {
+    if (!_setRange(start, end - start, from, startFrom)) {
       IterableMixinWorkaround.setRangeList(this, start,
-                                           length, from, startFrom);
+                                           end, from, startFrom);
     }
   }