close the input stream in build_mode tests so they dont hang

pkg/analyzer_cli/test/build_mode_test.dart

Index: pkg/analyzer_cli/test/build_mode_test.dart
diff --git a/pkg/analyzer_cli/test/build_mode_test.dart b/pkg/analyzer_cli/test/build_mode_test.dart
index f69a9f8e5dcabbc2c109906241ec440b0c91aab7..9c88a0f4e63d0513a51215b64ebde2effd8a1571 100644
--- a/pkg/analyzer_cli/test/build_mode_test.dart
+++ b/pkg/analyzer_cli/test/build_mode_test.dart
@@ -49,6 +49,7 @@ class WorkerLoopTest {
       'package:foo/bar.dart|/inputs/foo/lib/bar.dart',
     ]);
     stdinStream.addInputBytes(_serializeProto(request));
+    stdinStream.close();
 
     new TestAnalyzerWorkerLoop(connection, (CommandLineOptions options) {
       expect(options.buildSummaryInputs,
@@ -82,6 +83,7 @@ class WorkerLoopTest {
     var request = new WorkRequest();
     request.arguments.addAll(['--unknown-option', '/foo.dart', '/bar.dart']);
     stdinStream.addInputBytes(_serializeProto(request));
+    stdinStream.close();
     new TestAnalyzerWorkerLoop(connection).run();
     expect(connection.responses, hasLength(1));
 
@@ -92,6 +94,7 @@ class WorkerLoopTest {
 
   test_run_invalidRequest_noArgumentsInputs() {
     stdinStream.addInputBytes(_serializeProto(new WorkRequest()));
+    stdinStream.close();
 
     new TestAnalyzerWorkerLoop(connection).run();
     expect(connection.responses, hasLength(1));
@@ -103,6 +106,7 @@ class WorkerLoopTest {
 
   test_run_invalidRequest_randomBytes() {
     stdinStream.addInputBytes([1, 2, 3]);
+    stdinStream.close();
     new TestAnalyzerWorkerLoop(connection).run();
     expect(connection.responses, hasLength(1));
 
@@ -112,7 +116,7 @@ class WorkerLoopTest {
   }
 
   test_run_stopAtEOF() {
-    stdinStream.addInputBytes([-1]);
+    stdinStream.close();
     new TestAnalyzerWorkerLoop(connection).run();
   }
 }