D13215: Update sizes before generating frame svg background

[Vlad Zagorodniy]

zzag added a reviewer: Frameworks.

REPOSITORY
  R242 Plasma Framework (Library)

REVISION DETAIL
  https://phabricator.kde.org/D13215

To: zzag, #plasma, #frameworks
Cc: broulik, kde-frameworks-devel, michaelh, ngraham, bruns