[kernel] Debugging of switch statement

pkg/compiler/lib/src/kernel/kernel_visitor.dart

 // Copyright (c) 2016, 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.md file.
 
 import 'package:kernel/ast.dart' as ir;
 import 'package:kernel/frontend/accessors.dart'
     show
         Accessor,
         IndexAccessor,
         NullAwarePropertyAccessor,
@@ skipping 993 matching lines @@
 
   @override
   ir.StringConcatenation visitStringJuxtaposition(StringJuxtaposition node) {
     return new ir.StringConcatenation(
         <ir.Expression>[visitForValue(node.first), visitForValue(node.second)]);
   }
 
   @override
   ir.SwitchCase visitSwitchCase(SwitchCase node) {
     List<ir.Expression> expressions = <ir.Expression>[];
+    List<int> expressionOffsets = <int>[];
     for (var labelOrCase in node.labelsAndCases.nodes) {
       CaseMatch match = labelOrCase.asCaseMatch();
       if (match != null) {
-        expressions.add(visitForValue(match.expression));
+        ir.TreeNode expression = visitForValue(match.expression);
+        expressions.add(expression);
+        expressionOffsets.add(expression.fileOffset);
       } else {
         // Assert that labelOrCase is one of two known types: [CaseMatch] or
         // [Label]. We ignore cases, as any users have been resolved to use the
         // case directly.
         assert(labelOrCase.asLabel() != null);
       }
     }
     // We ignore the node's statements here, they're generated below in
     // [visitSwitchStatement] once we've set up all the jump targets.
     return associateNode(
-        new ir.SwitchCase(expressions, null, isDefault: node.isDefaultCase),
+        new ir.SwitchCase(expressions, expressionOffsets, null,
+            isDefault: node.isDefaultCase),
         node);
   }
 
   /// Returns true if [node] would let execution reach the next node (aka
   /// fall-through in switch cases).
   bool fallsThrough(ir.Statement node) {
     return !(node is ir.BreakStatement ||
         node is ir.ReturnStatement ||
         node is ir.ContinueSwitchStatement ||
         (node is ir.ExpressionStatement && node.expression is ir.Throw));
@@ skipping 1904 matching lines @@
       : this(null, true, node, initializers);
 
   accept(ir.Visitor v) => throw "unsupported";
 
   visitChildren(ir.Visitor v) => throw "unsupported";
 
   String toString() {
     return "IrFunction($kind, $isConstructor, $node, $initializers)";
   }
 }