Add incremental parser test for splitting a combinator.

pkg/analyzer/test/generated/parser_test.dart

Index: pkg/analyzer/test/generated/parser_test.dart
diff --git a/pkg/analyzer/test/generated/parser_test.dart b/pkg/analyzer/test/generated/parser_test.dart
index 1dc7170cf7a1f27ba5683bb228cfa014d5fd2aab..9414783c7356db815f47b88c76fa302381664d91 100644
--- a/pkg/analyzer/test/generated/parser_test.dart
+++ b/pkg/analyzer/test/generated/parser_test.dart
@@ -2799,6 +2799,12 @@ class IncrementalParserTest extends EngineTestCase {
     _assertParse("f() => a ", "+", "*", " b;");
   }
 
+  void test_split_combinator() {
+    // "import 'foo.dart' show A;"
+    // "import 'foo.dart' show B hide A;"
+    _assertParse("import 'foo.dart' show ", "", "B hide ", "A;");
+  }
+
   /**
    * Given a description of the original and modified contents, perform an incremental scan of the
    * two pieces of text.