internal/lsp: enable textDocument/implementation request

Change-Id: I0ff2d89a8f23de65f4ac4c732bfee69bf9df36a6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/204563
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Matloob <matloob@golang.org>
diff --git a/internal/lsp/general.go b/internal/lsp/general.go
index 0b408dd..42b7472 100644
--- a/internal/lsp/general.go
+++ b/internal/lsp/general.go
@@ -80,6 +80,8 @@
 				TriggerCharacters: []string{"."},
 			},
 			DefinitionProvider:         true,
+			TypeDefinitionProvider:     true,
+			ImplementationProvider:     true,
 			DocumentFormattingProvider: true,
 			DocumentSymbolProvider:     true,
 			ExecuteCommandProvider: &protocol.ExecuteCommandOptions{
@@ -101,7 +103,6 @@
 					IncludeText: false,
 				},
 			},
-			TypeDefinitionProvider: true,
 			Workspace: &struct {
 				WorkspaceFolders *struct {
 					Supported           bool   "json:\"supported,omitempty\""