builder: several fixups from comments

Docker-DCO-1.1-Signed-off-by: Erik Hollensbe <github@hollensbe.org> (github: erikh)
Upstream-commit: 305f73508022d0a3af65faa327aa798610969875
Component: engine

components/engine/builder/parser/line_parsers.go

@@ -116,18 +116,16 @@ func parseJSON(rest string) (*Node, map[string]bool, error) {
 func parseMaybeJSON(rest string) (*Node, map[string]bool, error) {
 	rest = strings.TrimSpace(rest)
 
-	if strings.HasPrefix(rest, "[") {
-		node, attrs, err := parseJSON(rest)
+	node, attrs, err := parseJSON(rest)
 
-		if err == nil {
-			return node, attrs, nil
-		}
-		if err == errDockerfileJSONNesting {
-			return nil, nil, err
-		}
+	if err == nil {
+		return node, attrs, nil
+	}
+	if err == errDockerfileJSONNesting {
+		return nil, nil, err
 	}
 
-	node := &Node{}
+	node = &Node{}
 	node.Value = rest
 	return node, nil, nil
 }

components/engine/builder/parser/parser.go

@@ -100,8 +100,7 @@ func Parse(rwc io.Reader) (*Node, error) {
 		}
 
 		if line != "" && child == nil {
-			for {
-				scanner.Scan()
+			for scanner.Scan() {
 				newline := strings.TrimSpace(scanner.Text())
 
 				if newline == "" {