Fix getSetterType in presence of metadata

tests/lib_strong/mirrors/field_metadata_test.dart

Index: tests/lib_strong/mirrors/field_metadata_test.dart
diff --git a/tests/lib_strong/mirrors/field_metadata_test.dart b/tests/lib_strong/mirrors/field_metadata_test.dart
index d64144dffbed799c8b0662409a82e6cc80b27987..a8db33dfb3c297d32d8954a6e397b18557543226 100644
--- a/tests/lib_strong/mirrors/field_metadata_test.dart
+++ b/tests/lib_strong/mirrors/field_metadata_test.dart
@@ -17,6 +17,11 @@ class Foo {
 
   @Bar('baz')
   final String y = 'hi';
+
+  @Bar('foo')
+  void set z(int val) {
+    x = val;
+  }
 }
 
 void main() {
@@ -28,6 +33,12 @@ void main() {
   Expect.equals(f.x, 42);
   Expect.equals(f.y, 'hi');
 
+  Expect.throws(() {
+    f.z = 'hello';
+  });
+  f.z = 0;
+  Expect.equals(f.x, 0);
+
   var members = reflect(f).type.declarations;
   var x = members[#x] as VariableMirror;
   var y = members[#y] as VariableMirror;