Mark --disallow-unsafe-eval as a supported feature in usage description.

sdk/lib/_internal/compiler/implementation/dart2js.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dart2js;
 
 import 'dart:async';
 import 'dart:collection' show Queue, LinkedHashMap;
 import 'dart:io';
 import 'dart:uri';
@@ skipping 388 matching lines @@
     code that is reachable from [main].  This option is useful for
     finding errors in libraries, but using it can result in bigger and
     slower output.
 
   --analyze-only
     Analyze but do not generate code.
 
   --minify
     Generate minified output.
 
+  --disallow-unsafe-eval
+    Disable dynamic generation of code in the generated output. This is
+    necessary to satisfy CSP restrictions (see http://www.w3.org/TR/CSP/).
+
   --suppress-warnings
     Do not display any warnings.
 
   --enable-diagnostic-colors
     Add colors to diagnostic messages.
 
 The following options are only used for compiler development and may
 be removed in a future version:
 
   --output-type=dart
     Output Dart code instead of JavaScript.
 
   --throw-on-error
     Throw an exception if a compile-time error is detected.
 
   --library-root=<directory>
     Where to find the Dart platform libraries.
 
   --allow-mock-compilation
     Do not generate a call to main if either of the following
     libraries are used: dart:dom, dart:html dart:io.
 
   --enable-concrete-type-inference
     Enable experimental concrete type inference.
 
   --disable-native-live-type-analysis
     Disable the optimization that removes unused native types from dart:html
     and related libraries.
 
-  --disallow-unsafe-eval
-    Disable dynamic generation of code in the generated output. This is
-    necessary to satisfy CSP restrictions (see http://www.w3.org/TR/CSP/).
-    This flag is not continuously tested. Please report breakages and we
-    will fix them as soon as possible.
-
   --reject-deprecated-language-features
     Reject deprecated language features.  Without this option, the
     compiler will accept language features that are no longer valid
     according to The Dart Programming Language Specification, version
     0.12, M1.
 
   --report-sdk-use-of-deprecated-language-features
     Report use of deprecated features in Dart platform libraries.
     Without this option, the compiler will silently accept use of
     deprecated language features from these libraries.  The option
@@ skipping 34 matching lines @@
     } catch (ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }