Create closed world for hello world using .dill file

pkg/compiler/lib/src/resolution/operators.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js.operators;
 
 import '../elements/elements.dart';
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/selector.dart' show Selector, SelectorKind;
 
@@ skipping 171 matching lines @@
   /// The binary | operator.
   static const BinaryOperator LOGICAL_OR =
       const _LogicalOperator(BinaryOperatorKind.LOGICAL_OR, '||');
 
   /// The if-null ?? operator.
   static const BinaryOperator IF_NULL =
       const _IfNullOperator(BinaryOperatorKind.IF_NULL, '??');
 
   static BinaryOperator parse(String value) {
     switch (value) {
+      case '&&':
+        return LOGICAL_AND;
+      case '||':
+        return LOGICAL_OR;
+      case '??':
+        return IF_NULL;
+      default:
+        return parseUserDefinable(value);
+    }
+  }
+
+  static BinaryOperator parseUserDefinable(String value) {
+    switch (value) {
       case '==':
         return EQ;
       case '!=':
         return NOT_EQ;
       case '[]':
         return INDEX;
       case '*':
         return MUL;
       case '/':
         return DIV;
@@ skipping 16 matching lines @@
       case '<=':
         return LTEQ;
       case '<':
         return LT;
       case '&':
         return AND;
       case '^':
         return XOR;
       case '|':
         return OR;
-      case '&&':
-        return LOGICAL_AND;
-      case '||':
-        return LOGICAL_OR;
-      case '??':
-        return IF_NULL;
       default:
         return null;
     }
   }
 
   // ignore: MISSING_RETURN
   static BinaryOperator fromKind(BinaryOperatorKind kind) {
     switch (kind) {
       case BinaryOperatorKind.EQ:
         return EQ;
@@ skipping 258 matching lines @@
   // ignore: MISSING_RETURN
   static IncDecOperator fromKind(IncDecOperatorKind kind) {
     switch (kind) {
       case IncDecOperatorKind.INC:
         return INC;
       case IncDecOperatorKind.DEC:
         return DEC;
     }
   }
 }