Drupal behaviors not running when element are shown

Patch attached.

@mherchel thanks for this patch, I am facing similar problem. On page load, the "Target field" (Text field) is not being shown even if the "Controlled By" field (Select List) value is set to show the "Target field" but once I change the value of the select list field it removes the style="display: none;" attribute, which displays the hidden field.

Sadly, the patch is not covering the aspect which I am mentioning.

@mherchel's patch above was broken by #3428532. Here's a re-roll and a MR.

Here's a static patch file version of MR70, for anyone who needs it.