Switch-implementation.

frog/leg/ssa/nodes.dart

Index: frog/leg/ssa/nodes.dart
diff --git a/frog/leg/ssa/nodes.dart b/frog/leg/ssa/nodes.dart
index c4c7e14041f971138a939ebeb68092ce124ca831..9be41041c7d7b99c8381e093128933b00d08d3dd 100644
--- a/frog/leg/ssa/nodes.dart
+++ b/frog/leg/ssa/nodes.dart
@@ -142,7 +142,7 @@ class HGraph {
     return result;
   }
 
-  HBasicBlock addNewLoopHeaderBlock(List<SourceString> labels) {
+  HBasicBlock addNewLoopHeaderBlock(List<LabelElement> labels) {
     HBasicBlock result = addNewBlock();
     result.loopInformation = new HLoopInformation(result, labels);
     return result;
@@ -433,9 +433,6 @@ class HBasicBlock extends HInstructionList {
   HBasicBlock dominator = null;
   final List<HBasicBlock> dominatedBlocks;
 
-  // For recognizing labeled statements.
-  List<SourceString> labels;
-
   HBasicBlock() : this.withId(null);
   HBasicBlock.withId(this.id)
       : phis = new HInstructionList(),
@@ -669,7 +666,7 @@ class HBlockInformation {
 class HLabeledBlockInformation extends HBlockInformation {
   final SubGraph body;
   final HBasicBlock joinBlock;
-  final List<SourceString> labels;
+  final List<LabelElement> labels;
   HLabeledBlockInformation(this.body, this.joinBlock, this.labels);
 }
 
@@ -677,7 +674,7 @@ class HLoopInformation extends HBlockInformation {
   final HBasicBlock header;
   final List<HBasicBlock> blocks;
   final List<HBasicBlock> backEdges;
-  final List<SourceString> labels;
+  final List<LabelElement> labels;
 
   HLoopInformation(this.header, this.labels)
       : blocks = new List<HBasicBlock>(),
@@ -1665,9 +1662,9 @@ class HGoto extends HControlFlow {
 }
 
 class HBreak extends HGoto {
-  final SourceString label;
+  final LabelElement label;
   HBreak([this.label]);
-  toString() => 'break';
+  toString() => label === null ? 'break' : 'break ${label.labelName}';
   accept(HVisitor visitor) => visitor.visitBreak(this);
 }