dart2js: CPS translation of switches with continue to their labels.

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 e2c8e603ee986bf9f009ecfecc6661419b3cc132..5250c7985d3673f6332839d9c4c71154c2dd0fb2 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
@@ -30,6 +30,7 @@ class SExpressionStringifier extends Indentation implements Visitor<String> {
   }
 
   String access(Reference<Definition> r) {
+    if (r == null) return '**** NULL ****';
     return decorator(r, namer.getName(r.definition));
   }
 
@@ -48,7 +49,11 @@ class SExpressionStringifier extends Indentation implements Visitor<String> {
   /// Main entry point for creating a [String] from a [Node].  All recursive
   /// calls must go through this method.
   String visit(Node node) {
-    if (node == null) return '**** NULL ****';
+    if (node == null) {
+      return node is Expression

[asgerf, 2016/01/19 22:45:24]

Dead code, null is not an expression.

[Kevin Millikin (Google), 2016/01/25 12:46:37]

Done.

+          ? '$indentation**** NULL ****'
+          : '**** NULL ****';
+    }
     String s = node.accept(this);
     return decorator(node, s);
   }
@@ -192,7 +197,9 @@ class SExpressionStringifier extends Indentation implements Visitor<String> {
   String visitInvokeContinuation(InvokeContinuation node) {
     String name = access(node.continuation);
     if (node.isRecursive) name = 'rec $name';
-    String args = node.arguments.map(access).join(' ');
+    String args = node.arguments == null
+        ? '**** NULL ****'
+	: node.arguments.map(access).join(' ');
     String escaping = node.isEscapingTry ? ' escape' : '';
     return '$indentation(InvokeContinuation $name ($args)$escaping)';
   }