Handler the last native annotations

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

Index: pkg/compiler/lib/src/constants/evaluation.dart
diff --git a/pkg/compiler/lib/src/constants/evaluation.dart b/pkg/compiler/lib/src/constants/evaluation.dart
index 8fefead9b5312acec86fc5d60051b4fc1f7c54bc..8721230e4ae74bc421d3d1200c209b80e135fe0f 100644
--- a/pkg/compiler/lib/src/constants/evaluation.dart
+++ b/pkg/compiler/lib/src/constants/evaluation.dart
@@ -4,6 +4,7 @@
 
 library dart2js.constants.evaluation;
 
+import '../common.dart';
 import '../common/backend_api.dart' show BackendClasses;
 import '../core_types.dart' show CommonElements;
 import '../elements/entities.dart';
@@ -52,17 +53,62 @@ class NormalizedArguments {
     int index = callStructure.namedArguments.indexOf(name);
     if (index == -1) {
       // The named argument is not provided.
+      invariant(CURRENT_ELEMENT_SPANNABLE, defaultValues[name] != null,
+          message: "No default value for named argument '$name' in $this.");
       return defaultValues[name];
     }
-    return arguments[index + callStructure.positionalArgumentCount];
+    ConstantExpression value =
+        arguments[index + callStructure.positionalArgumentCount];
+    invariant(CURRENT_ELEMENT_SPANNABLE, value != null,
+        message: "No value for named argument '$name' in $this.");
+    return value;
   }
 
   /// Returns the normalized [index]th positional argument.
   ConstantExpression getPositionalArgument(int index) {
     if (index >= callStructure.positionalArgumentCount) {
       // The positional argument is not provided.
+      invariant(CURRENT_ELEMENT_SPANNABLE, defaultValues[index] != null,
+          message: "No default value for positional argument $index in $this.");
       return defaultValues[index];
     }
-    return arguments[index];
+    ConstantExpression value = arguments[index];
+    invariant(CURRENT_ELEMENT_SPANNABLE, value != null,
+        message: "No value for positional argument $index in $this.");
+    return value;
+  }
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.write('NormalizedArguments[');
+    sb.write('defaultValues={');
+    bool needsComma = false;
+    defaultValues.forEach((var key, ConstantExpression value) {
+      if (needsComma) {
+        sb.write(',');
+      }
+      if (key is String) {
+        sb.write('"');
+        sb.write(key);
+        sb.write('"');
+      } else {
+        sb.write(key);
+      }
+      sb.write(':');
+      sb.write(value.toStructuredText());
+      needsComma = true;
+    });
+    sb.write('},callStructure=');
+    sb.write(callStructure);
+    sb.write(',arguments=[');
+    arguments.forEach((ConstantExpression value) {
+      if (needsComma) {
+        sb.write(',');
+      }
+      sb.write(value.toStructuredText());
+      needsComma = true;
+    });
+    sb.write(']]');
+    return sb.toString();
   }
 }