When trying to add different alt tags to different images, the alloy-editor always takes to the last entry

[georgel-pop-lr]

I want to report a bug.

Steps to reproduce:

1. set default editor in portal-ext.properties as the following
   editor.wysiwyg.default=alloyeditor
   editor.wysiwyg.portal-impl.portlet.ddm.text_html.ftl=alloyeditor
2. start the bundle and log in as admin
3. go to Content and Data --> Web content, then add a new one
4. using AlloyEditor's add image button add at least two images to the content
5. set different alt tags for the images using the toolbar's Alt setting part
6. click on AlloyEditor image toolbar Alt setting part and check its textbox

Expected result:
AlloyEditor image toolbar Alt setting part should show the same tags which have been set individually for each of the images and are visible in the source mode.

Actual result:
AlloyEditor image toolbar Alt setting part shows the last entered alt tag for all images, although in source mode the originally set tags are presented.

Video reproducing the issue: https://issues.liferay.com/secure/attachment/433420/PTR-2775.mp4

For more details, please check: https://issues.liferay.com/browse/LPS-143258