Revert "Don't use Error.toSafeString in List constructor."

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 1b78b32d343cd25eb64cb1492c4c62de784d16d8..67e59fb1ac5726e4a22ec604be93a9954c7e94ff 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
@@ -487,10 +487,16 @@ class Primitives {
   }
 
   static List newGrowableList(length) {
+    // TODO(sra): For good concrete type analysis we need the JS-type to
+    // specifically name the JavaScript Array implementation.  'List' matches
+    // all the dart:html types that implement List<T>.
     return JS('=List', r'new Array(#)', length);
   }
 
   static List newFixedList(length) {
+    // TODO(sra): For good concrete type analysis we need the JS-type to
+    // specifically name the JavaScript Array implementation.  'List' matches
+    // all the dart:html types that implement List<T>.
     var result = JS('=List', r'new Array(#)', length);
     JS('void', r'#.fixed$length = #', result, true);
     return result;