Support for stack traces in catch blocks.

frog/leg/lib/js_helper.dart

Index: frog/leg/lib/js_helper.dart
===================================================================
--- frog/leg/lib/js_helper.dart	(revision 4945)
+++ frog/leg/lib/js_helper.dart	(working copy)
@@ -1303,3 +1303,13 @@
   }
   return ex;
 }
+
+class StackTrace {

[ahe, 2012/03/06 08:44:22]

This class is hidden from users (because it is defined in this file). Is it
supposed to be part of coreimpl?

[ngeoffray, 2012/03/06 12:12:50]

The StackTrace class/interface is not in core, nor in coreimpl. I belive it
should be in the core library.

+  var stack;
+  StackTrace(this.stack);
+  toString() => stack != null ? stack : '';

[floitsch, 2012/03/06 10:22:32]

Please type toString as returning a String.

[ngeoffray, 2012/03/06 12:12:50]

Done.

+}
+
+getTraceFromException(exception) {

[ahe, 2012/03/06 08:44:22]

Please add a documentation comment that explains where this is called from.

[ngeoffray, 2012/03/06 12:12:50]

Done.

+  return new StackTrace(JS("var", @"$0.stack", exception));

[ahe, 2012/03/06 08:44:22]

Nice. I didn't realize you could use "var" here. But I guess it is obvious.

+}