Fixes #254 - Better stacktrace support

lib/runtime/dart/mirrors.js

 dart_library.library('dart/mirrors', null, /* Imports */[
   "dart_runtime/dart",
   'dart/core'
 ], /* Lazy imports */[
   'dart/_js_mirrors'
 ], function(exports, dart, core, _js_mirrors) {
   'use strict';
   let dartx = dart.dartx;
   class MirrorSystem extends core.Object {
     findLibrary(libraryName) {
@@ skipping 19 matching lines @@
   function currentMirrorSystem() {
     return dart.as(_js_mirrors.currentJsMirrorSystem, MirrorSystem);
   }
   dart.fn(currentMirrorSystem, MirrorSystem, []);
   function reflect(reflectee) {
     return _js_mirrors.reflect(reflectee);
   }
   dart.fn(reflect, () => dart.definiteFunctionType(InstanceMirror, [core.Object]));
   function reflectClass(key) {
     if (!dart.is(key, core.Type) || dart.equals(key, dart.dynamic)) {
-      throw new core.ArgumentError(`${key} does not denote a class`);
+      dart.throw(new core.ArgumentError(`${key} does not denote a class`));
     }
     let tm = reflectType(key);
     if (!dart.is(tm, ClassMirror)) {
-      throw new core.ArgumentError(`${key} does not denote a class`);
+      dart.throw(new core.ArgumentError(`${key} does not denote a class`));
     }
     return dart.as(dart.as(tm, ClassMirror).originalDeclaration, ClassMirror);
   }
   dart.fn(reflectClass, () => dart.definiteFunctionType(ClassMirror, [core.Type]));
   function reflectType(key) {
     if (dart.equals(key, dart.dynamic)) {
       return currentMirrorSystem().dynamicType;
     }
     return _js_mirrors.reflectType(key);
   }
@@ skipping 76 matching lines @@
   exports.FunctionTypeMirror = FunctionTypeMirror;
   exports.TypeVariableMirror = TypeVariableMirror;
   exports.TypedefMirror = TypedefMirror;
   exports.MethodMirror = MethodMirror;
   exports.VariableMirror = VariableMirror;
   exports.ParameterMirror = ParameterMirror;
   exports.SourceLocation = SourceLocation;
   exports.Comment = Comment;
   exports.MirrorsUsed = MirrorsUsed;
 });