Use computeConstantValue instead of constantValue

pkg/dev_compiler/lib/src/compiler/code_generator.dart

Index: pkg/dev_compiler/lib/src/compiler/code_generator.dart
diff --git a/pkg/dev_compiler/lib/src/compiler/code_generator.dart b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
index 76292e44a0094bd56c23647772c75b82cc9d4bb2..a23e3e3231364ffa597584c29138e42fff158429 100644
--- a/pkg/dev_compiler/lib/src/compiler/code_generator.dart
+++ b/pkg/dev_compiler/lib/src/compiler/code_generator.dart
@@ -4448,7 +4448,7 @@ class CodeGenerator extends GeneralizingAstVisitor
       Element staticElement = identifier.staticElement;
       if (staticElement is PropertyAccessorElement && staticElement.isGetter) {
         PropertyInducingElement variable = staticElement.variable;
-        int value = variable?.constantValue?.toIntValue();
+        int value = variable?.computeConstantValue()?.toIntValue();
         if (value != null && value >= low && value <= high) return value;
       }
       return null;