Handle deferred access of unserialized code.

pkg/compiler/lib/src/deferred_load.dart

Index: pkg/compiler/lib/src/deferred_load.dart
diff --git a/pkg/compiler/lib/src/deferred_load.dart b/pkg/compiler/lib/src/deferred_load.dart
index 18e85adfe2095ba5700e8b2dc03286d757c2d4cf..0f4f8d74eefbb56c0e34a9ee46dfdd154b1785de 100644
--- a/pkg/compiler/lib/src/deferred_load.dart
+++ b/pkg/compiler/lib/src/deferred_load.dart
@@ -349,6 +349,13 @@ class DeferredLoadTask extends CompilerTask {
         // See dartbug.com/26406 for context.
         treeElements
             .forEachConstantNode((Node node, ConstantExpression expression) {
+          if (compiler.serialization.isDeserialized(analyzableElement)) {
+            if (!expression.isImplicit && !expression.isPotential) {
+              // Enforce evaluation of [expression].
+              backend.constants.getConstantValue(expression);
+            }
+          }
+
           // Explicitly depend on the backend constants.
           if (backend.constants.hasConstantValue(expression)) {
             ConstantValue value =