Fix cast exception when a Handle gets a wrong element because of name conflict.

pkg/analyzer/lib/src/summary/link.dart

Index: pkg/analyzer/lib/src/summary/link.dart
diff --git a/pkg/analyzer/lib/src/summary/link.dart b/pkg/analyzer/lib/src/summary/link.dart
index 7a348354efa021830680e19a9b621fbdec2b476a..8640a71aba0e1aaeb12371a1379370c317314b1f 100644
--- a/pkg/analyzer/lib/src/summary/link.dart
+++ b/pkg/analyzer/lib/src/summary/link.dart
@@ -1056,7 +1056,9 @@ abstract class CompilationUnitElementForLink
               resolveRef(containingReference).getContainedName(name);
         }
       } else if (linkedReference.dependency == 0) {
-        if (name == 'void') {
+        if (linkedReference.kind == ReferenceKind.unresolved) {
+          _references[index] = UndefinedElementForLink.instance;
+        } else if (name == 'void') {
           _references[index] = enclosingElement._linker.voidElement;
         } else if (name == '*bottom*') {
           _references[index] = enclosingElement._linker.bottomElement;