Update mirror tests for removed API.

tests/lib/mirrors/operator_test.dart

Index: tests/lib/mirrors/operator_test.dart
diff --git a/tests/lib/mirrors/operator_test.dart b/tests/lib/mirrors/operator_test.dart
index 54367b15277af333945f21df18f6dd5199ed7182..c534f1ff514481b263bfebe1a9ef47d7329ffbda 100644
--- a/tests/lib/mirrors/operator_test.dart
+++ b/tests/lib/mirrors/operator_test.dart
@@ -42,7 +42,8 @@ void main() {
   var operators = new Map<Symbol, MethodMirror>();
   var operatorParameters = new Map<Symbol, List>();
   var returnTypes =  new Map<Symbol, Mirror>();
-  for (MethodMirror method in cls.methods.values) {
+  for (MethodMirror method in cls.declarations.values.where(
+      (d) => d is MethodMirror && !d.isConstructor)) {
     Expect.isTrue(method.isRegularMethod);
     Expect.isTrue(method.isOperator);
     Expect.isFalse(method.isGetter);