Refactor removeRange.

runtime/lib/array.dart

Index: runtime/lib/array.dart
diff --git a/runtime/lib/array.dart b/runtime/lib/array.dart
index 1aa5bba291223623fb93e14287aabc842d901ee2..ef49b7eec28dc6dfd1dfc274775e56095ad324e3 100644
--- a/runtime/lib/array.dart
+++ b/runtime/lib/array.dart
@@ -81,7 +81,7 @@ class _ObjectArray<E> implements List<E> {
     }
   }
 
-  void removeRange(int start, int length) {
+  void removeRange(int start, int end) {
     throw new UnsupportedError(
         "Cannot remove range of a non-extendable array");
   }
@@ -313,7 +313,7 @@ class _ImmutableArray<E> implements List<E> {
         "Cannot modify an immutable array");
   }
 
-  void removeRange(int start, int length) {
+  void removeRange(int start, int end) {
     throw new UnsupportedError(
         "Cannot remove range of an immutable array");
   }