Add `=` as default-value separator for named parameters.

runtime/vm/parser.cc

 // 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.
 
 #include "vm/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 2167 matching lines @@
 
   if ((CurrentToken() == Token::kASSIGN) || (CurrentToken() == Token::kCOLON)) {
     if ((!params->has_optional_positional_parameters &&
          !params->has_optional_named_parameters) ||
         !allow_explicit_default_value) {
       ReportError("parameter must not specify a default value");
     }
     if (params->has_optional_positional_parameters) {
       ExpectToken(Token::kASSIGN);
     } else {
-      ExpectToken(Token::kCOLON);
+      ConsumeToken();
     }
     params->num_optional_parameters++;
     params->has_explicit_default_values = true;  // Also if explicitly NULL.
     if (is_top_level_) {
       // Skip default value parsing.
       SkipExpr();
     } else {
       const Instance& const_value = ParseConstExpr()->literal();
       parameter.default_value = &const_value;
     }
@@ skipping 12886 matching lines @@
     const ArgumentListNode& function_args,
     const LocalVariable* temp_for_last_arg,
     bool is_super_invocation) {
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME