Fix issue 12023 by avoiding a critical edge in the SSA graph with a switch statement.

sdk/lib/_internal/compiler/implementation/ssa/nodes.dart

Index: sdk/lib/_internal/compiler/implementation/ssa/nodes.dart
===================================================================
--- sdk/lib/_internal/compiler/implementation/ssa/nodes.dart	(revision 26117)
+++ sdk/lib/_internal/compiler/implementation/ssa/nodes.dart	(working copy)
@@ -2695,16 +2695,12 @@
   final HExpressionInformation expression;
   final List<List<Constant>> matchExpressions;
   final List<HStatementInformation> statements;
-  // If the switch has a default, it's the last statement block, which
-  // may or may not have other expresions.
-  final bool hasDefault;
   final TargetElement target;
   final List<LabelElement> labels;
 
   HSwitchBlockInformation(this.expression,
                           this.matchExpressions,
                           this.statements,
-                          this.hasDefault,
                           this.target,
                           this.labels);