Add dummy dart:html library for documentation.

Add dummy dart:html library for documentation.

dartdoc will be added in the fake dart:html library in lib/html/doc
and merged into the real dart:html library during dart:html build.

We will be adding a tool to that can be run as part of the dart:html build to
merge in the documentation.  The tool will also be able to run stand-alone to
update the documentation post-build.  This will allow documentation work to
continue independently of building.

Committed: https://code.google.com/p/dart/source/detail?r=8415

[vsm, 2012-06-08 01:32:04]

LGTM with comments and '.dart' -> '.dartdoc' as discussed.

https://chromiumcodereview.appspot.com/10544064/diff/1/lib/html/doc/html.dart
File lib/html/doc/html.dart (right):

https://chromiumcodereview.appspot.com/10544064/diff/1/lib/html/doc/html.dart...
lib/html/doc/html.dart:7: /// Hahaha!
Remove.  :-)

https://chromiumcodereview.appspot.com/10544064/diff/1/lib/html/doc/html.dart...
lib/html/doc/html.dart:562: // Implementation files that appear to be necessary
to load the sources.
Add a comment "Only private classes appear below.  These don't require
documentation here."

https://chromiumcodereview.appspot.com/10544064/diff/1/lib/html/doc/interface...
File lib/html/doc/interface/AbstractWorker.dart (right):

https://chromiumcodereview.appspot.com/10544064/diff/1/lib/html/doc/interface...
lib/html/doc/interface/AbstractWorker.dart:5: // WARNING: Do not edit -
generated code.
Can you drop these?  Editing is the whole point.  :-)