Document --analyze-all option.

dart/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:io';
 import 'dart:uri';
 import 'dart:utf';
 
@@ skipping 357 matching lines @@
 
   -h, /h, /?, --help
     Display this message (add -v for information about all options).
 
   -v, --verbose
     Display verbose information.
 
   -p<path>, --package-root=<path>
     Where to find packages, that is, "package:..." imports.
 
+  --analyze-all
+    Normally, the compiler only examines code that is reachable from
+    [main].  With this option, it will examine everything.  This is

[asandholm, 2012/11/14 12:46:25]

LGTM with comments. 
I'd probably use "analyze" rather than "examine". Start with what the option
does (not what the default behavior is). The extra info on where this is useful
and the added cost on perf is nice-to-have but not need-to-have IMO.

+    useful for finding errors in libraries, but using this option can
+    result in bigger and slower output.
+
   --minify
     Generate minified output.
 
   --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
@@ skipping 46 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.
     }
   }
 }