Add an analysis option to disable cache flushing.

pkg/analyzer_cli/test/options_test.dart

Index: pkg/analyzer_cli/test/options_test.dart
diff --git a/pkg/analyzer_cli/test/options_test.dart b/pkg/analyzer_cli/test/options_test.dart
index b74edc16fd241c2770f593219fb89c5731bb070a..a062657dcbad3f10cb3a4ef353a118ad13ab9301 100644
--- a/pkg/analyzer_cli/test/options_test.dart
+++ b/pkg/analyzer_cli/test/options_test.dart
@@ -27,6 +27,7 @@ main() {
         expect(options.buildSummaryOutputSemantic, isNull);
         expect(options.buildSuppressExitCode, isFalse);
         expect(options.dartSdkPath, isNotNull);
+        expect(options.disableCacheFlushing, isFalse);
         expect(options.disableHints, isFalse);
         expect(options.lints, isFalse);
         expect(options.displayVersion, isFalse);
@@ -60,6 +61,12 @@ main() {
         expect(options.definedVariables['bar'], isNull);
       });
 
+      test('disable cache flushing', () {
+        CommandLineOptions options = CommandLineOptions
+            .parse(['--dart-sdk', '.', '--disable-cache-flushing', 'foo.dart']);
+        expect(options.disableCacheFlushing, isTrue);
+      });
+
       test('enable strict call checks', () {
         CommandLineOptions options = CommandLineOptions.parse(
             ['--dart-sdk', '.', '--enable-strict-call-checks', 'foo.dart']);