Bug fix for issue 4256

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 10015)
+++ compiler/java/com/google/dart/compiler/parser/DartParser.java	(working copy)
@@ -1744,6 +1744,9 @@
       // Ensure termination if token is anything other than COMMA.
       // Must keep Token.COMMA in sync with @Terminals above
       if (!optional(Token.COMMA)) {
+        if (isNamed && !optional(Token.RBRACK)) {
+          reportErrorWithoutAdvancing(ParserErrorCode.MISSING_NAMED_PARAMETER_END);
+        }
         // Must keep Token.RPAREN in sync with @Terminals above
         expectCloseParen();
         done = true;