Refactor removeRange.

runtime/lib/array.dart

Index: runtime/lib/array.dart
diff --git a/runtime/lib/array.dart b/runtime/lib/array.dart
index fe18eab4abf674b149533e3ace08aefc34844dee..6dea0f301d2ee272f4987c5932f0efef4d26b11d 100644
--- a/runtime/lib/array.dart
+++ b/runtime/lib/array.dart
@@ -80,7 +80,7 @@ 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");
   }
@@ -326,7 +326,7 @@ 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");
   }