Accept more labels per switch case.

lib/compiler/implementation/tree/unparser.dart

Index: lib/compiler/implementation/tree/unparser.dart
diff --git a/lib/compiler/implementation/tree/unparser.dart b/lib/compiler/implementation/tree/unparser.dart
index 17852756cf2781af25b2609512899147492ac7cb..d48774e9a91761c6792a8cdbc9077bc6ea90d3f4 100644
--- a/lib/compiler/implementation/tree/unparser.dart
+++ b/lib/compiler/implementation/tree/unparser.dart
@@ -347,14 +347,26 @@ class Unparser implements Visitor {
   }
 
   visitSwitchCase(SwitchCase node) {
-    if (node.label !== null) {
-      visit(node.label);
-      sb.add(': ');
+    Link<Label> labels = node.labels.nodes;
+    Link<CaseMatch> cases = node.cases.nodes;
+    // Interleave labels and cases in their original order.
+    while (!labels.isEmpty()) {
+      Label label = labels.head;
+      while (!cases.isEmpty()) {
+        CaseMatch match = cases.head;
+        if (match.colonToken.charOffset < label.colonToken.charOffset) {
+          visit(match);
+          cases = cases.tail;
+        } else {
+          break;
+        }
+      }
+      visit(label);
+      labels = labels.tail;
     }
-    for (Expression expression in node.expressions) {
-      sb.add('case ');
-      visit(expression);
-      sb.add(': ');
+    while (!cases.isEmpty()) {
+      visit(cases.head);
+      cases = cases.tail;
     }
     if (node.isDefaultCase) {
       sb.add('default:');
@@ -389,6 +401,13 @@ class Unparser implements Visitor {
     }
   }
 
+  visitCaseMatch(CaseMatch node) {
+    add(node.caseKeyword.value);
+    sb.add(" ");
+    visit(node.expression);
+    add(node.colonToken.value);
+  }
+
   visitCatchBlock(CatchBlock node) {
     add(node.catchKeyword.value);
     sb.add(' ');