Fix the build

compiler/java/com/google/dart/compiler/parser/DartParser.java

Index: compiler/java/com/google/dart/compiler/parser/DartParser.java
===================================================================
--- compiler/java/com/google/dart/compiler/parser/DartParser.java	(revision 13023)
+++ compiler/java/com/google/dart/compiler/parser/DartParser.java	(working copy)
@@ -2302,7 +2302,10 @@
     if (token == Token.CASCADE) {
       List<DartExpression> cascadeSections = new ArrayList<DartExpression>();
       while (token == Token.CASCADE) {
-        cascadeSections.add(parseCascadeSection());
+        DartExpression section = parseCascadeSection();
+        if (section != null) {
+          cascadeSections.add(section);
+        }
         token = peek(0);
       }
       result = done(new DartCascadeExpression(result, cascadeSections));