Make more use of generated code in analysis server.

Make more use of generated code in analysis server.

The following generated classes are now used:
- CompletionRelevance
- CompletionSuggestion
- CompletionSuggestionKind
- ErrorFixes
- HighlightRegion
- HighlightRegionType
- HoverInformation
- LinkedEditGroup
- LinkedEditSuggestion
- LinkedEditSuggestionKind
- SourceChange

Generated code is used to produce these notifications:
- analysis.errors
- analysis.highlights
- analysis.navigation
- search.results
- server.error
- server.status

Generated code is used to produce the response to these requests:
- analysis.getErrors
- analysis.getHover
- edit.getAssists
- edit.getFixes
- server.getVersion

Generated code is used to handle these notifications in unit testing:
- analysis.highlights
- analysis.navigation

In addition, these methods have been removed, since they are no longer
needed:
- Notification.getParameter
- Result.setEmptyResult
- Result.setResult

R=brianwilkerson@google.com

Committed: https://code.google.com/p/dart/source/detail?r=39511

[Paul Berry, 2014-08-24 05:08:04]

With this CL, I believe the generated code is used nearly everywhere in analysis
server now.  There are only a few loose ends left to clean up.

[Brian Wilkerson, 2014-08-24 07:58:05]

LGTM

[Paul Berry, 2014-08-24 08:40:34]

Committed patchset #1 manually as 39511 (presubmit successful).