Merge pull request #3863 from rosslaird/spelling

Corrected spelling error

less/navbar.less

@@ -14,7 +14,7 @@
   margin-bottom: @baseLineHeight;
 }
 
-// Gradient is applied to it's own element because overflow visible is not honored by IE when filter is present
+// Gradient is applied to its own element because overflow visible is not honored by IE when filter is present
 .navbar-inner {
   min-height: @navbarHeight;
   padding-left:  20px;
@@ -358,4 +358,4 @@
     left: auto;
     right: 13px;
   }
-}
\ No newline at end of file
+}