Resolve initializers in their proper scope.

dart/frog/leg/compile_time_constants.dart

Index: dart/frog/leg/compile_time_constants.dart
diff --git a/dart/frog/leg/compile_time_constants.dart b/dart/frog/leg/compile_time_constants.dart
index c4d932b2cc919f28d4130e860bb5a8a758a00fc7..bee8dfaf6a812bd6fde67c4ee25ac446a7279845 100644
--- a/dart/frog/leg/compile_time_constants.dart
+++ b/dart/frog/leg/compile_time_constants.dart
@@ -934,6 +934,8 @@ class CompileTimeConstantEvaluator extends AbstractVisitor {
   }
 
   Constant visitNewExpression(NewExpression node) {
+    Element currentElement = compiler.currentElement;
+
     void assignArgumentsToParameters(
         FunctionParameters parameters,
         Map<Element, Constant> constructorDefinitions,
@@ -999,7 +1001,9 @@ class CompileTimeConstantEvaluator extends AbstractVisitor {
         }
       }
       if (classElement.superclass != compiler.coreLibrary.find(Types.OBJECT)) {
-        compiler.unimplemented("ConstantHandler with super", node: node);
+        compiler.withCurrentElement(currentElement, () {
+          compiler.unimplemented("ConstantHandler with super", node: node);
+        });
       }
       return jsNewArguments;
     }