Change getRange to sublist. Make getRange deprecated.

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

Index: sdk/lib/_internal/compiler/implementation/lib/js_array.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/js_array.dart b/sdk/lib/_internal/compiler/implementation/lib/js_array.dart
index 10059c788a114df3c6396617c70f4cb1819b0969..07620a4aac9f490ca8adcf3f7d658af2997d6b43 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/js_array.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/js_array.dart
@@ -137,23 +137,30 @@ class JSArray<E> implements List<E>, JSIndexable {
     return this[index];
   }
 
-  List<E> getRange(int start, int length) {
-    // TODO(ngeoffray): Parameterize the return value.
-    if (0 == length) return [];
+  List<E> sublist(int start, [int end]) {
     checkNull(start); // TODO(ahe): This is not specified but co19 tests it.
-    checkNull(length); // TODO(ahe): This is not specified but co19 tests it.
     if (start is !int) throw new ArgumentError(start);
-    if (length is !int) throw new ArgumentError(length);
-    if (length < 0) throw new ArgumentError(length);
-    if (start < 0) throw new RangeError.value(start);
-    int end = start + length;
-    if (end > this.length) {
-      throw new RangeError.value(length);
+    if (start < 0 || start > length) {
+      throw new RangeError.range(start, 0, length);
     }
-    if (length < 0) throw new ArgumentError(length);
+    if (end == null) {
+      end = length;
+    } else {
+      if (end is !int) throw new ArgumentError(end);
+      if (end < start || end > length) {
+        throw new RangeError.range(end, start, length);
+      }
+    }
+    // TODO(ngeoffray): Parameterize the return value.
+    if (start == end) return [];
     return JS('=List', r'#.slice(#, #)', this, start, end);
   }
 
+
+  List<E> getRange(int start, int length) {
+    return sublist(start, start + length);
+  }
+
   void insertRange(int start, int length, [E initialValue]) {
     checkGrowable(this, 'insertRange');
     if (length == 0) {