Reapply "Allow LetCont to bind multiple continuations."

pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart

Index: pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
index c4d5f1f0fd53144106b4512c83a93d530d9b637d..8c16f58c7249a96280d75fa49da8945803d1fec5 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_tracer.dart
@@ -112,8 +112,10 @@ class IRTracer extends TracerUtil implements cps_ir.Visitor {
   visitLetCont(cps_ir.LetCont node) {
     if (IR_TRACE_LET_CONT) {
       String dummy = names.name(node);
-      String id = names.name(node.continuation);
-      printStmt(dummy, "LetCont $id = <$id>");
+      for (cps_ir.Continuation continuation in node.continuations) {
+        String id = names.name(continuation);
+        printStmt(dummy, "LetCont $id = <$id>");
+      }
     }
     visit(node.body);
   }
@@ -422,7 +424,7 @@ class BlockCollector extends cps_ir.Visitor {
   }
 
   visitLetCont(cps_ir.LetCont exp) {
-    visit(exp.continuation);
+    exp.continuations.forEach(visit);
     visit(exp.body);
   }