textDocument/declaration missing a ServerCapabilities indicator

[sam-mccall]

definitionProvider, typeDefinitionProvider etc exist - is the absence of declarationProvider an oversight?

Would be useful e.g. here: https://github.com/Valloric/ycmd/blob/5996d7daf2fda93ba2a0f6cfa86cf7c99e20170a/ycmd/completers/language_server/language_server_completer.py#L59

[ioeric]

ping?

This is blocking go-to-declaration support in some clients (e.g. YCM).

[rcjsuen]

Since it exists in the Microsoft/vscode-languageserver-node repository, it looks like an oversight to me.

[rcjsuen]

I've opened #701 to hopefully address this.

[dbaeumer]

@rcjsuen thanks. Merged the PR.