Keep only InterfaceType(s) in resynthesized lists of interfaces and mixins.

pkg/analyzer/test/src/summary/resynthesize_test.dart

Index: pkg/analyzer/test/src/summary/resynthesize_test.dart
diff --git a/pkg/analyzer/test/src/summary/resynthesize_test.dart b/pkg/analyzer/test/src/summary/resynthesize_test.dart
index 4a378a05f3bb11f7d25e1dbe75c1bef55d84bdc8..764294d23545f61a146ed4c051aa8295d043cc1b 100644
--- a/pkg/analyzer/test/src/summary/resynthesize_test.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_test.dart
@@ -1722,6 +1722,11 @@ class E {}''');
     checkLibrary('class C implements D, E {} class D {} class E {}');
   }
 
+  test_class_interfaces_unresolved() {
+    checkLibrary('class C implements X, Y, Z {} class X {} class Z {}',
+        allowErrors: true);
+  }
+
   test_class_method_abstract() {
     checkLibrary('abstract class C { f(); }');
   }
@@ -1746,6 +1751,11 @@ class E {}''');
     checkLibrary('class C extends Object with D, E {} class D {} class E {}');
   }
 
+  test_class_mixins_unresolved() {
+    checkLibrary('class C extends Object with X, Y, Z; class X {} class Z {}',
+        allowErrors: true);
+  }
+
   test_class_setter_abstract() {
     checkLibrary('abstract class C { void set x(int value); }');
   }