Fix 'Unused local variable' hints in analyzer and analysis_server.

pkg/analyzer/bin/analyzer.dart

Index: pkg/analyzer/bin/analyzer.dart
diff --git a/pkg/analyzer/bin/analyzer.dart b/pkg/analyzer/bin/analyzer.dart
index c7efb78d2aecad18107c905448ec4ecebce59378..bf1ce785e0a8e4448a8eec65bb420ba873a46ae8 100644
--- a/pkg/analyzer/bin/analyzer.dart
+++ b/pkg/analyzer/bin/analyzer.dart
@@ -107,7 +107,7 @@ class BatchRunner {
     Stream cmdLine = stdin
         .transform(UTF8.decoder)
         .transform(new LineSplitter());
-    var subscription = cmdLine.listen((String line) {
+    cmdLine.listen((String line) {
       // may be finish
       if (line.isEmpty) {
         var time = stopwatch.elapsedMilliseconds;