Issue 4040. Fix NPE when report problem with no node.

compiler/javatests/com/google/dart/compiler/parser/NegativeParserTest.java

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 package com.google.dart.compiler.parser;
 
 import com.google.common.base.Joiner;
 import com.google.dart.compiler.CompilerTestCase;
 import com.google.dart.compiler.ast.DartClass;
 import com.google.dart.compiler.ast.DartIdentifier;
 import com.google.dart.compiler.ast.DartMethodDefinition;
@@ skipping 61 matching lines @@
         errEx(ParserErrorCode.REDIRECTING_CONSTRUCTOR_ITSELF, 1, 39, 7));
   }
 
   public void testMultipleRedirectionConstructors() {
     parseExpectErrors(
         "class A { A(x) { } A.foo() : this(1), this(2); }",
         errEx(ParserErrorCode.REDIRECTING_CONSTRUCTOR_MULTIPLE, 1, 30, 7),
         errEx(ParserErrorCode.REDIRECTING_CONSTRUCTOR_MULTIPLE, 1, 39, 7));
   }
 
+  /**
+   * May be parsing errors, but not exceptions.
+   * <p>
+   * http://code.google.com/p/dart/issues/detail?id=4040
+   */
+  public void test_incompleteArguments() {
+    parseSource(makeCode(
+        "// filler filler filler filler filler filler filler filler filler filler",
+        "main() {",
+        "  f(a: 0,",
+        "}",
+        ""));
+  }
+
   public void testSuperMultipleInvocationsTest() {
     String source =
         makeCode(
             "class A {",
             "    int a;",
             "    A(this.a);",
             "    A.foo(int x, int y);",
             "}",
             "",
             "class B extends A {",
@@ skipping 926 matching lines @@
   public void test_qualifiedType_inForIn() {
     parseExpectErrors(Joiner.on("\n").join(
         "// filler filler filler filler filler filler filler filler filler filler",
         "foo() {",
         "  for (pref.A a in elements) {",
         "  }",
         "}",
         ""));
   }
 }