Revert "Simplify and fix implicit closure check, speed up Closure_equals"

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 1071 matching lines @@
   const Script& script = Script::Handle(zone, func.script());
   Parser parser(script, parsed_function, func.token_pos());
 #ifndef PRODUCT
   if (tds.enabled()) {
     tds.SetNumArguments(1);
     tds.CopyArgument(0, "function", String::Handle(func.name()).ToCString());
   }
 #endif  // !PRODUCT
   SequenceNode* node_sequence = NULL;
   switch (func.kind()) {
-    case RawFunction::kImplicitClosureFunction:
-      node_sequence = parser.ParseImplicitClosure(func);
-      break;
     case RawFunction::kClosureFunction:
+      if (func.IsImplicitClosureFunction()) {
+        node_sequence = parser.ParseImplicitClosure(func);
+        break;
+      }
       if (func.IsConstructorClosureFunction()) {
         node_sequence = parser.ParseConstructorClosure(func);
         break;
       }
     // Fall-through: Handle non-implicit closures.
     case RawFunction::kRegularFunction:
     case RawFunction::kGetterFunction:
     case RawFunction::kSetterFunction:
     case RawFunction::kConstructor:
       // The call to a redirecting factory is redirected.
@@ skipping 13994 matching lines @@
 bool Parser::FieldHasFunctionLiteralInitializer(const Field& field,
                                                 TokenPosition* start,
                                                 TokenPosition* end) {
   UNREACHABLE();
   return false;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME