Move Arrays class to private library.

sdk/lib/_internal/compiler/implementation/lib/js_helper.dart

Index: sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
index 353c7880e50417772036d572c9ede59b92f1c3cc..f9a3af7c6ad148cf9a58ef529b71e0abd36bb8bc 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
@@ -561,32 +561,6 @@ ioore(index) {
   throw new RangeError.value(index);
 }
 
-listInsertRange(receiver, start, length, initialValue) {
-  if (length == 0) {
-    return;
-  }
-  if (length is !int) throw new ArgumentError(length);
-  if (length < 0) throw new ArgumentError(length);
-  if (start is !int) throw new ArgumentError(start);
-
-  var receiverLength = JS('num', r'#.length', receiver);
-  if (start < 0 || start > receiverLength) {
-    throw new RangeError.value(start);
-  }
-  receiver.length = receiverLength + length;
-  Arrays.copy(receiver,
-              start,
-              receiver,
-              start + length,
-              receiverLength - start);
-  if (initialValue != null) {
-    for (int i = start; i < start + length; i++) {
-      receiver[i] = initialValue;
-    }
-  }
-  receiver.length = receiverLength + length;
-}
-
 stringLastIndexOfUnchecked(receiver, element, start)
   => JS('int', r'#.lastIndexOf(#, #)', receiver, element, start);