Reapply "Allow LetCont to bind multiple continuations."

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

Index: pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
diff --git a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
index 8496f54f37743d52f384703ade6b070735b4922f..e18e01781df19fdd56e89370ee6e907aba3fc0bf 100644
--- a/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
+++ b/pkg/compiler/lib/src/cps_ir/cps_ir_nodes_sexpr.dart
@@ -76,20 +76,31 @@ class SExpressionStringifier extends Visitor<String> with Indentation {
   }
 
   String visitLetCont(LetCont node) {
-    String cont = newContinuationName(node.continuation);
-    // TODO(karlklose): this should be changed to `.map(visit).join(' ')`  and
-    // should recurse to [visit].  Currently we can't do that, because the
-    // unstringifier_test produces [LetConts] with dummy arguments on them.
-    String parameters = node.continuation.parameters
-        .map((p) => '${decorator(p, newValueName(p))}')
-        .join(' ');
-    String contBody =
-        indentBlock(() => indentBlock(() => visit(node.continuation.body)));
+    String conts;
+    bool first = true;
+    for (Continuation continuation in node.continuations) {
+      String name = newContinuationName(continuation);
+      if (continuation.isRecursive) name = 'rec $name';
+      // TODO(karlklose): this should be changed to `.map(visit).join(' ')`  and
+      // should recurse to [visit].  Currently we can't do that, because the
+      // unstringifier_test produces [LetConts] with dummy arguments on them.
+      String parameters = continuation.parameters
+          .map((p) => '${decorator(p, newValueName(p))}')
+          .join(' ');
+      String body =
+          indentBlock(() => indentBlock(() => visit(continuation.body)));
+      if (first) {
+        first = false;
+        conts = '($name ($parameters)\n$body)';
+      } else {
+        // Each subsequent line is indented additional spaces to align it
+        // with the previous continuation.
+        String indent = '$indentation${' ' * '(LetCont ('.length}';
+        conts = '$conts\n$indent($name ($parameters)\n$body)';
+      }
+    }
     String body = indentBlock(() => visit(node.body));
-    String op = node.continuation.isRecursive ? 'LetCont*' : 'LetCont';
-    return '$indentation($op ($cont ($parameters)\n'
-           '$contBody)\n'
-           '$body)';
+    return '$indentation($LetCont ($conts)\n$body)';
   }
 
   String formatArguments(Invoke node) {
@@ -99,7 +110,7 @@ class SExpressionStringifier extends Visitor<String> with Indentation {
         node.arguments.getRange(0, positionalArgumentCount).map(access));
     for (int i = 0; i < node.selector.namedArgumentCount; ++i) {
       String name = node.selector.namedArguments[i];
-      Definition arg = node.arguments[positionalArgumentCount + i].definition;
+      String arg = access(node.arguments[positionalArgumentCount + i]);
       args.add("($name: $arg)");
     }
     return '(${args.join(' ')})';