Use failedAt in more places (constants, universe)

pkg/compiler/lib/src/constants/expressions.dart

Index: pkg/compiler/lib/src/constants/expressions.dart
diff --git a/pkg/compiler/lib/src/constants/expressions.dart b/pkg/compiler/lib/src/constants/expressions.dart
index 1b7079dfe4008ccfe02219d543a5ea33c6db1849..1387ca4e48e35aadc25b0e0fbce8387326229fbc 100644
--- a/pkg/compiler/lib/src/constants/expressions.dart
+++ b/pkg/compiler/lib/src/constants/expressions.dart
@@ -560,8 +560,8 @@ class ConstructedConstantExpression extends ConstantExpression {
       EvaluationEnvironment environment) {
     ConstantConstructor constantConstructor =
         environment.getConstructorConstant(target);
-    assert(invariant(target, constantConstructor != null,
-        message: "No constant constructor computed for $target."));
+    assert(constantConstructor != null,
+        failedAt(target, "No constant constructor computed for $target."));
     return constantConstructor.computeInstanceFields(
         environment, arguments, callStructure);
   }