Add stacktrace_test

pkg/compiler/lib/src/io/position_information.dart

 // Copyright (c) 2015, 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.
 
 /// Source information system mapping that attempts a semantic mapping between
 /// offsets of JavaScript code points to offsets of Dart code points.
 
 library dart2js.source_information.position;
 
 import '../common.dart';
@@ skipping 504 matching lines @@
 class PositionTraceListener extends TraceListener
     with NodeToSourceInformationMixin {
   final SourceMapper sourceMapper;
 
   PositionTraceListener(this.sourceMapper);
 
   @override
   void onStep(js.Node node, Offset offset, StepKind kind) {
     SourceInformation sourceInformation = computeSourceInformation(node);
     if (sourceInformation == null) return;
-    int codeLocation = offset.subexpressionOffset;
+    int codeLocation = offset.value;
     if (codeLocation == null) return;
 
     void registerPosition(SourcePositionKind sourcePositionKind) {
       SourceLocation sourceLocation =
           getSourceLocation(sourceInformation, sourcePositionKind);
       if (sourceLocation != null) {
         sourceMapper.register(node, codeLocation, sourceLocation);
       }
     }
 
@@ skipping 133 matching lines @@
   ///     ^                   // the left-to-right offset of the `baz()` call
   ///
   /// Here, `baz()` is executed before `foo()` so we need to use 'f' as its best
   /// position under the restriction.
   ///
   final int leftToRightOffset;
 
   Offset(
       this.statementOffset, this.leftToRightOffset, this.subexpressionOffset);
 
+  int get value => subexpressionOffset;
+
   String toString() {
     return 'Offset[statementOffset=$statementOffset,'
         'leftToRightOffset=$leftToRightOffset,'
         'subexpressionOffset=$subexpressionOffset]';
   }
 }
 
 enum BranchKind { CONDITION, LOOP, CATCH, FINALLY, CASE, }
 
 enum StepKind {
@@ skipping 588 matching lines @@
 
   @override
   CodePosition operator [](js.Node node) {
     CodePosition codePosition = codePositions[node];
     if (codePosition == null) {
       coverage.registerNodesWithoutOffset(node);
     }
     return codePosition;
   }
 }