readline: move the "setRawMode" logic into a private function

lib/readline.js

@@ -108,9 +108,7 @@ function Interface(input, output, completer, terminal) {
     // Current line
     this.line = '';
 
-    if (typeof input.setRawMode === 'function') {
-      input.setRawMode(true);
-    }
+    this._setRawMode(true);
     this.terminal = true;
 
     // Cursor position on the line.
@@ -143,6 +141,13 @@ Interface.prototype.setPrompt = function(prompt, length) {
 };
 
 
+Interface.prototype._setRawMode = function(mode) {
+  if (typeof this.input.setRawMode === 'function') {
+    return this.input.setRawMode(mode);
+  }
+}
+
+
 Interface.prototype.prompt = function(preserveCursor) {
   if (this.paused) this.resume();
   if (this.terminal) {
@@ -239,9 +244,7 @@ Interface.prototype._refreshLine = function() {
 Interface.prototype.close = function() {
   if (this.closed) return;
   if (this.terminal) {
-    if (typeof this.input.setRawMode === 'function') {
-      this.input.setRawMode(false);
-    }
+    this._setRawMode(false);
   }
   this.pause();
   this.closed = true;