Support going to type definition with tsserver (#3545)

autoload/ale/definition.vim

@@ -36,7 +36,7 @@ function! ale#definition#UpdateTagStack() abort
 endfunction
 
 function! ale#definition#HandleTSServerResponse(conn_id, response) abort
-    if get(a:response, 'command', '') is# 'definition'
+    if has_key(a:response, 'request_seq')
     \&& has_key(s:go_to_definition_map, a:response.request_seq)
         let l:options = remove(s:go_to_definition_map, a:response.request_seq)
 
@@ -92,11 +92,19 @@ function! s:OnReady(line, column, options, capability, linter, lsp_details) abor
     call ale#lsp#RegisterCallback(l:id, l:Callback)
 
     if a:linter.lsp is# 'tsserver'
-        let l:message = ale#lsp#tsserver_message#Definition(
-        \   l:buffer,
-        \   a:line,
-        \   a:column
-        \)
+        if a:capability is# 'definition'
+            let l:message = ale#lsp#tsserver_message#Definition(
+            \   l:buffer,
+            \   a:line,
+            \   a:column
+            \)
+        elseif a:capability is# 'typeDefinition'
+            let l:message = ale#lsp#tsserver_message#TypeDefinition(
+            \   l:buffer,
+            \   a:line,
+            \   a:column
+            \)
+        endif
     else
         " Send a message saying the buffer has changed first, or the
         " definition position probably won't make sense.
@@ -145,12 +153,6 @@ endfunction
 function! ale#definition#GoToType(options) abort
     for l:linter in ale#linter#Get(&filetype)
         if !empty(l:linter.lsp)
-            " TODO: handle typeDefinition for tsserver if supported by the
-            " protocol
-            if l:linter.lsp is# 'tsserver'
-                continue
-            endif
-
             call s:GoToLSPDefinition(l:linter, a:options, 'typeDefinition')
         endif
     endfor

autoload/ale/lsp.vim

@@ -357,6 +357,7 @@ function! ale#lsp#MarkConnectionAsTsserver(conn_id) abort
     let l:conn.capabilities.completion = 1
     let l:conn.capabilities.completion_trigger_characters = ['.']
     let l:conn.capabilities.definition = 1
+    let l:conn.capabilities.typeDefinition = 1
     let l:conn.capabilities.symbol_search = 1
     let l:conn.capabilities.rename = 1
     let l:conn.capabilities.code_actions = 1

autoload/ale/lsp/tsserver_message.vim

@@ -64,6 +64,14 @@ function! ale#lsp#tsserver_message#Definition(buffer, line, column) abort
     \}]
 endfunction
 
+function! ale#lsp#tsserver_message#TypeDefinition(buffer, line, column) abort
+    return [0, 'ts@typeDefinition', {
+    \   'line': a:line,
+    \   'offset': a:column,
+    \   'file': expand('#' . a:buffer . ':p'),
+    \}]
+endfunction
+
 function! ale#lsp#tsserver_message#References(buffer, line, column) abort
     return [0, 'ts@references', {
     \   'line': a:line,