Change --hide-package-warnings to --show-package-warnings and add hint on suppress warnings.

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

Index: sdk/lib/_internal/compiler/implementation/dart2js.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart2js.dart b/sdk/lib/_internal/compiler/implementation/dart2js.dart
index b44541509d61898caba2c840451aa51e13d98d03..022b0e5873233bec4075f838d4313da58ab0dea2 100644
--- a/sdk/lib/_internal/compiler/implementation/dart2js.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart2js.dart
@@ -279,7 +279,7 @@ Future compile(List<String> argv) {
     new OptionHandler('--dump-info', passThrough),
     new OptionHandler('--disallow-unsafe-eval',
                       (_) => hasDisallowUnsafeEval = true),
-    new OptionHandler('--hide-package-warnings', passThrough),
+    new OptionHandler('--show-package-warnings', passThrough),
     new OptionHandler('-D.+=.*', addInEnvironment),
 
     // The following two options must come last.
@@ -558,8 +558,9 @@ Supported options:
     Emit diagnostics without suggestions for how to get rid of the diagnosed
     problems.
 
-  --hide-package-warnings
-    Hide warnings and hints generated from packages.
+  --show-package-warnings
+    Show warnings and hints generated from packages that are not directly

[floitsch, 2014/03/03 13:30:23]

What does "directly analyzed" mean?

I would keep the old text (unless you come up with something good).

[Johnni Winther, 2014/03/03 13:40:26]

"directly analyzed" means given as entry point. If you run

dart2js package:foo/bar.dart

then warnings from 'package:foo' will always be shown.

+    analyzed by dart2js.
 
 The following options are only used for compiler development and may
 be removed in a future version: