All initializer expressions are serialized, even if not all of them are constants.

pkg/analyzer/lib/src/summary/resynthesize.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 summary_resynthesizer;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
@@ skipping 268 matching lines @@
   int doublePtr = 0;
   int stringPtr = 0;
   int refPtr = 0;
   final List<Expression> stack = <Expression>[];
 
   _ConstExprBuilder(this.resynthesizer, this.uc);
 
   Expression get expr => stack.single;
 
   Expression build() {
-    if (!uc.isValidConst) {
-      return AstFactory.identifier3(r'$$invalidConstExpr$$');
-    }
     for (UnlinkedConstOperation operation in uc.operations) {
       switch (operation) {
         case UnlinkedConstOperation.pushNull:
           _push(AstFactory.nullLiteral());
           break;
         // bool
         case UnlinkedConstOperation.pushFalse:
           _push(AstFactory.booleanLiteral(false));
           break;
         case UnlinkedConstOperation.pushTrue:
@@ skipping 255 matching lines @@
 
   void _pushBinary(TokenType operator) {
     Expression right = _pop();
     Expression left = _pop();
     _push(AstFactory.binaryExpression(left, operator, right));
   }
 
   void _pushExtractProperty() {
     Expression target = _pop();
     String name = uc.strings[stringPtr++];
-    // TODO(scheglov) Only String.length property access is supported.
-    assert(name == 'length');
-    _push(AstFactory.propertyAccess(
-        target,
-        AstFactory.identifier3('length')
-          ..staticElement = _getStringLengthElement()));
+    SimpleIdentifier propertyNode = AstFactory.identifier3(name);
+    // Only String.length property access can be potentially resolved.
+    if (name == 'length') {
+      propertyNode.staticElement = _getStringLengthElement();
+    }
+    _push(AstFactory.propertyAccess(target, propertyNode));
   }
 
   void _pushInstanceCreation() {
     EntityRef ref = uc.references[refPtr++];
     _ReferenceInfo info = resynthesizer.referenceInfos[ref.reference];
     // prepare ConstructorElement
     TypeName typeNode;
     String constructorName;
     ConstructorElement constructorElement;
     if (info.element != null) {
@@ skipping 2064 matching lines @@
   static String _getElementIdentifier(String name, ReferenceKind kind) {
     if (kind == ReferenceKind.topLevelPropertyAccessor ||
         kind == ReferenceKind.propertyAccessor) {
       if (!name.endsWith('=')) {
         return name + '?';
       }
     }
     return name;
   }
 }