Ensure libraries always have at least one top-level class and therefore at least one script.

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 "lib/invocation_mirror.h"
 #include "platform/utils.h"
 #include "vm/ast_transformer.h"
 #include "vm/bootstrap.h"
@@ skipping 5952 matching lines @@
         ParseTopLevelFunction(&top_level, metadata_pos);
       } else if (IsTopLevelAccessor()) {
         ParseTopLevelAccessor(&top_level, metadata_pos);
       } else if (CurrentToken() == Token::kEOS) {
         break;
       } else {
         UnexpectedToken();
       }
     }
   }
-  if ((top_level.fields.Length() > 0) || (top_level.functions.Length() > 0)) {
-    toplevel_class.AddFields(top_level.fields);
 
-    const Array& array = Array::Handle(Z,
-                                       Array::MakeArray(top_level.functions));
-    toplevel_class.SetFunctions(array);
+  toplevel_class.AddFields(top_level.fields);
 
-    library_.AddAnonymousClass(toplevel_class);
-    pending_classes.Add(toplevel_class, Heap::kOld);
-  }
+  const Array& array = Array::Handle(Z, Array::MakeArray(top_level.functions));
+  toplevel_class.SetFunctions(array);
+
+  library_.AddAnonymousClass(toplevel_class);

[hausner, 2015/05/19 05:43:03]

A library with 100 part files will now have 100 top-level classes, right?
Instead of creating a TL class unconditionally, you could change the old code
to:

if ((library_ has no top-level classes) || 
    (top_level.fields.Length() > 0) || (top_level.functions.Length() > 0)) {
....

[rmacnak, 2015/05/19 15:57:41]

Done.

+  pending_classes.Add(toplevel_class, Heap::kOld);
 }
 
 
 void Parser::ChainNewBlock(LocalScope* outer_scope) {
   Block* block = new(Z) Block(
       current_block_,
       outer_scope,
       new(Z) SequenceNode(TokenPos(), outer_scope));
   current_block_ = block;
 }
@@ skipping 7482 matching lines @@
 void Parser::SkipQualIdent() {
   ASSERT(IsIdentifier());
   ConsumeToken();
   if (CurrentToken() == Token::kPERIOD) {
     ConsumeToken();  // Consume the kPERIOD token.
     ExpectIdentifier("identifier expected after '.'");
   }
 }
 
 }  // namespace dart