Use isValidConst flag to distinguish between const / final expressions.

pkg/analyzer/lib/src/summary/link.dart

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index ae63ef8f7a22e93d0adedf785edfb6dc45800d97..54e6d689ddcd20f4f5821c6657d13fca7cca1801 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -2290,7 +2290,7 @@ class TypeInferenceNode extends Node<TypeInferenceNode> {
   void evaluate(bool inCycle) {
     if (inCycle) {
       _inferredType = DynamicTypeImpl.instance;
-    } else if (variableElement.unlinkedVariable.constExpr.isInvalid) {
+    } else if (!variableElement.unlinkedVariable.constExpr.isValidConst) {
       // TODO(paulberry): implement.

[Paul Berry, 2016/04/05 21:19:33]

So that I don't become confused later, would you mind changing to:

// TODO(paulberry): delete this case and fix errors.

(This code does type inference, so it shouldn't distinguish between valid and
invalid consts).

Thanks!

[scheglov, 2016/04/05 21:26:26]

Done.

       throw new UnimplementedError();
     } else {