Work around issue 15920 in pkg/stack_trace.

pkg/stack_trace/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.
 
 library trace;
 
 import 'dart:collection';
 import 'dart:math' as math;
 
 import 'chain.dart';
@@ skipping 108 matching lines @@
       // IE and Safari, where the stack trace is just an empty string (issue
       // 11257).
       return new Trace.parseVM(trace);
     } on FormatException catch (error) {
       throw new FormatException('${error.message}\nStack trace:\n$trace');
     }
   }
 
   /// Parses a string representation of a Dart VM stack trace.
   Trace.parseVM(String trace)
-      : this(trace.trim().split("\n").map((line) => new Frame.parseVM(line)));
+      : this(trace.trim().split("\n").
+            // TODO(nweiz): remove this when issue 15920 is fixed.
+            where((line) => line.isNotEmpty).

[Bob Nystrom, 2014/01/06 21:42:49]

Should you trim the line first in case it contains only whitespace?

[nweiz, 2014/01/06 23:59:27]

I'm pretty sure that in practice the blank lines produced by the VM never have
any whitespace. Since this code just exists to work around those, I don't think
it's necessary.

+            map((line) => new Frame.parseVM(line)));
 
   /// Parses a string representation of a Chrome/V8 stack trace.
   Trace.parseV8(String trace)
       : this(trace.split("\n").skip(1)
           // It's possible that an Exception's description contains a line that
           // looks like a V8 trace line, which will screw this up.
           // Unfortunately, that's impossible to detect.
           .skipWhile((line) => !line.startsWith(_v8TraceLine))
           .map((line) => new Frame.parseV8(line)));
 
@@ skipping 97 matching lines @@
     // Figure out the longest path so we know how much to pad.
     var longest = frames.map((frame) => frame.location.length)
         .fold(0, math.max);
 
     // Print out the stack trace nicely formatted.
     return frames.map((frame) {
       return '${padRight(frame.location, longest)}  ${frame.member}\n';
     }).join();
   }
 }