Refactor removeRange.

sdk/lib/collection/list.dart

Index: sdk/lib/collection/list.dart
diff --git a/sdk/lib/collection/list.dart b/sdk/lib/collection/list.dart
index 4b9e0f1ec5b1a0b4104585a21fc3c0670b589fe1..84d9208f21b94ea77c08c17d73732d7340e1d12e 100644
--- a/sdk/lib/collection/list.dart
+++ b/sdk/lib/collection/list.dart
@@ -342,14 +342,14 @@ abstract class ListMixin<E> implements List<E> {
     }
   }
 
-  void removeRange(int start, int length) {
+  void removeRange(int start, int end) {
     if (start < 0 || start > this.length) {
       throw new RangeError.range(start, 0, this.length);
     }
-    if (length < 0 || start + length > this.length) {
-      throw new RangeError.range(length, 0, this.length - start);
+    if (end < start || end > this.length) {
+      throw new RangeError.range(end, start, this.length);
     }
-    int end = start + length;
+    int length = end - start;
     setRange(start, this.length - length, this, end);
     this.length -= length;
   }