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..6349c30a1a290d1ddc24bb81f403ac5db1786ddb 100644
--- a/lib/compiler/implementation/tree/unparser.dart
+++ b/lib/compiler/implementation/tree/unparser.dart
@@ -347,15 +347,7 @@ class Unparser implements Visitor {
   }
 
   visitSwitchCase(SwitchCase node) {
-    if (node.label !== null) {
-      visit(node.label);
-      sb.add(': ');
-    }
-    for (Expression expression in node.expressions) {
-      sb.add('case ');
-      visit(expression);
-      sb.add(': ');
-    }
+    visit(node.labelsAndCases);
     if (node.isDefaultCase) {
       sb.add('default:');
     }
@@ -389,6 +381,13 @@ 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(' ');