Fix error recovery for extracting native name.

pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart

Index: pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart
diff --git a/pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart b/pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart
index 6acc1c3ea7f35710da391270cd92ab274410f90b..ce766765e524b363d5718ab497ceb47a39a638fe 100644
--- a/pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart
+++ b/pkg/front_end/lib/src/fasta/parser/dart_vm_native.dart
@@ -45,6 +45,7 @@ Token skipNativeClause(Token token) {
 /// This method designed to be called from [Listener.handleMemberName].
 Link<Token> removeNativeClause(Link<Token> identifiers) {
   Link<Token> result = identifiers.tail;
+  if (result.isEmpty) return identifiers;
   if (result.head.kind != STRING_TOKEN) return identifiers;
   result = result.tail;
   if (result.isEmpty) return identifiers;