Forward port CMS 7458 to 7.9: Image cropper preview not shown for "large" image variants

When cropping a ‘large’ image, large as in width 460px, height 345px, the crop image dialog works not as expected. For ‘small’ images a preview is shown in the crop image dialog, for large images this preview isn’t shown. See attachments.

Reproduction:

• Login in the gogreen
• Goto Images
• Goto events/2013/03/ CalifornianAcademyScience.jpg
• Click edit
• Crop the image variant “Thumbnail (large)”
• Preview not shown
• Crop another image variant, e.g. “Logo (mobile)”
• Preview shown

Related versions:
Gogreen version: 3.07.07
CMS version: 2.24.06