Trace.current skips an extra frame in JS.

lib/src/trace.dart

 // Copyright (c) 2013, 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.
 
 import 'dart:math' as math;
 
 import 'chain.dart';
 import 'frame.dart';
 import 'lazy_trace.dart';
 import 'unparsed_frame.dart';
@@ skipping 63 matching lines @@
   /// By default, the first frame of this trace will be the line where
   /// [Trace.current] is called. If [level] is passed, the trace will start that
   /// many frames up instead.
   factory Trace.current([int level=0]) {
     if (level < 0) {
       throw new ArgumentError("Argument [level] must be greater than or equal "
           "to 0.");
     }
 
     var trace = new Trace.from(StackTrace.current);
-    return new LazyTrace(() => new Trace(trace.frames.skip(level + 1)));
+    return new LazyTrace(() {
+      // JS includes a frame for the call to StackTrace.current, but the VM
+      // doesn't, so we skip an extra frame in a JS context.
+      return new Trace(trace.frames.skip(level + (inJS ? 2 : 1)));
+    });
   }
 
   /// Returns a new stack trace containing the same data as [trace].
   ///
   /// If [trace] is a native [StackTrace], its data will be parsed out; if it's
   /// a [Trace], it will be returned as-is.
   factory Trace.from(StackTrace trace) {
     // Normally explicitly validating null arguments is bad Dart style, but here
     // the natural failure will only occur when the LazyTrace is materialized,
     // and we want to provide an error that's more local to the actual problem.
@@ skipping 189 matching lines @@
     var longest = frames.map((frame) => frame.location.length)
         .fold(0, math.max);
 
     // Print out the stack trace nicely formatted.
     return frames.map((frame) {
       if (frame is UnparsedFrame) return "$frame\n";
       return '${padRight(frame.location, longest)}  ${frame.member}\n';
     }).join();
   }
 }