dart2js cps: Direct access on JS arrays.

pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart

Index: pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
diff --git a/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart b/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
index fb62a729fe33195f03afce7a434c0e94b079bd55..f1970de0d0271ade7f88d180aef863f94f5e57c9 100644
--- a/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
+++ b/pkg/compiler/lib/src/cps_ir/shrinking_reductions.dart
@@ -676,6 +676,21 @@ class ParentVisitor extends RecursiveVisitor {
     }
     node.arguments.forEach((Reference ref) => ref.parent = node);
   }
+
+  processGetLength(GetLength node) {
+    node.object.parent = node;
+  }
+
+  processGetIndex(GetIndex node) {
+    node.object.parent = node;
+    node.index.parent = node;
+  }
+
+  processSetIndex(SetIndex node) {
+    node.object.parent = node;
+    node.index.parent = node;
+    node.value.parent = node;
+  }
 }
 
 class _ReductionKind {