Merge pull request #261 from bbshih/patch-1

Fixed a grammatical error

javascript.html.markdown

@@ -342,7 +342,7 @@ myPrototype.meaningOfLife = 43;
 myObj.meaningOfLife; // = 43
 
 // We mentioned that __proto__ was non-standard, and there's no standard way to
-// change the prototype of an existing object. However, there's two ways to
+// change the prototype of an existing object. However, there are two ways to
 // create a new object with a given prototype.
 
 // The first is Object.create, which is a recent addition to JS, and therefore