internal/lsp/source: fix type modifier detection in composite literals

When completing a composite literal value, we were returning from
candidate inference before we recorded type modifiers such as prefix
"&" or "*". This was causing funny completions like:

type myStruct struct { s *myStruct }
myStruct{s: &mySt<> // completed to "&&myStruct{}"

Now we properly pick up on the "&" prefix so we know our literal
"myStruct{}" candidate does not need a "&".

Change-Id: I908936698cfedfef81bc0c1cbcd93e14dc00e3a3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/218377
Run-TryBot: Muir Manders <muir@mnd.rs>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/source/completion.go

@@ -1329,7 +1329,6 @@ func expectedCandidate(c *completer) (inf candidateInference) {
 
 	if c.enclosingCompositeLiteral != nil {
 		inf.objType = c.expectedCompositeLiteralType()
-		return inf
 	}
 
 Nodes:

internal/lsp/testdata/lsp/primarymod/snippets/literal_snippets.go.in

@@ -180,3 +180,15 @@ func _() {
 	var mi myInt
 	mi = my //@snippet(" //", litMyInt, "myInt($0)", "myInt($0)")
 }
+
+func _() {
+	type ptrStruct struct {
+		p *ptrStruct
+	}
+
+	ptrStruct{} //@item(litPtrStruct, "ptrStruct{}", "", "var")
+
+	ptrStruct{
+		p: &ptrSt, //@rank(",", litPtrStruct)
+	}
+}