restore js label to orphan code blocks

docs/api/dialog.md

@@ -41,7 +41,7 @@ otherwise it returns `undefined`.
 The `filters` specifies an array of file types that can be displayed or
 selected when you want to limit the user to a specific type. For example:
 
-```
+```js
 {
   filters: [
     {name: 'Images', extensions: ['jpg', 'png', 'gif']},

docs/api/menu.md

@@ -359,7 +359,7 @@ the first item.
 
 Template:
 
-```
+```js
 [
   {label: '4', id: '4'},
   {label: '5', id: '5'},
@@ -381,7 +381,7 @@ Menu:
 
 Template:
 
-```
+```js
 [
   {label: 'a', position: 'endof=letters'},
   {label: '1', position: 'endof=numbers'},

docs/api/web-contents.md

@@ -843,7 +843,7 @@ The `callback` will be called with `callback(error, data)` on completion. The
 
 By default, an empty `options` will be regarded as:
 
-```
+```js
 {
   marginsType: 0,
   printBackground: false,

docs/api/web-frame.md

@@ -119,7 +119,7 @@ console.log(webFrame.getResourceUsage())
 
 This will generate:
 
-```
+```js
 {
   images: {
     count: 22,
@@ -133,7 +133,7 @@ This will generate:
   xslStyleSheets: { /* same with "images" */ },
   fonts: { /* same with "images" */ },
   other: { /* same with "images" */ }
-})
+}
 ```
 
 ### `webFrame.clearCache()`