Fixes #254 - Better stacktrace support

lib/runtime/_operations.js

Index: lib/runtime/_operations.js
diff --git a/lib/runtime/_operations.js b/lib/runtime/_operations.js
index 6f9294edfe6a23ecfbcd9e8454f66cec48ac1458..f6012f42c6981e1aaac137ba48fcfbad006c9ed1 100644
--- a/lib/runtime/_operations.js
+++ b/lib/runtime/_operations.js
@@ -269,12 +269,22 @@ dart_library.library('dart_runtime/_operations', null, /* Imports */[
   }
   exports.assert = assert;
 
-  function throw_(obj) { throw obj; }
+  let _stack = Symbol('_stack');
+
+  function throw_(obj) {
+    obj[_stack] = new Error();
+    throw obj;
+  }
   exports.throw_ = throw_;

[Jennifer Messerly, 2015/07/13 16:39:17]

btw, this should be `throw` ... all names work for properties

[vsm, 2015/07/14 13:54:48]

Done.

 
+  function rethrow(obj) {

[Jennifer Messerly, 2015/07/13 16:39:17]

if this doesn't do anything, why have the helper?

[vsm, 2015/07/14 13:54:48]

Removed

+    throw obj;
+  }
+  exports.rethrow = rethrow;
 
   function stackTrace(exception) {
-    return _js_helper.getTraceFromException(exception);
+    var error = _stack in exception ? exception[_stack] : exception;
+    return _js_helper.getTraceFromException(error);
   }
   exports.stackTrace = stackTrace;