Addition of AnalysisServer.isSocketOpen for clients to know if the server is still running.

pkg/analysis_server/tool/spec/codegen_analysis_server.dart

Index: pkg/analysis_server/tool/spec/codegen_analysis_server.dart
diff --git a/pkg/analysis_server/tool/spec/codegen_analysis_server.dart b/pkg/analysis_server/tool/spec/codegen_analysis_server.dart
index e491f69f7ecb50634aaa4507790df502c5afeb95..2559d1a34f36b4627ec98f29f94ab7effcba296b 100644
--- a/pkg/analysis_server/tool/spec/codegen_analysis_server.dart
+++ b/pkg/analysis_server/tool/spec/codegen_analysis_server.dart
@@ -78,6 +78,17 @@ class CodegenAnalysisServer extends CodegenJavaVisitor {
       });
 
       //
+      // isSocketOpen()
+      //
+      publicMethod('isSocketOpen', () {
+              writeln('''/**
+ * Return {@code true} if the socket is open.
+ */''');
+        writeln(
+          'public boolean isSocketOpen();');
+        });
+
+      //
       // start(..)
       //
       publicMethod('start', () {