Summary:
give frameSvg the concept of repaintBlocked(), that enables and
disables the regeneration of the frame data when a property is set.
the use case is when often, a lot of properties are set one after
the other (such as prefix, enabled borders, size)
collapse the formely similar, but a bit different logic of frame
regeneration is a single function for better maintanability.
QML FrameSvgItem sets repaintblocked when it starts and releases it just on oncomponentCompleted
Test Plan:
plasmashell still starts, autotests still work, all frames are rendered correctly
the destruction of old frames is cutted by 50%. in the qml profiler
the creation time of a framesvgitem slightly improved, on this machine from around 26 msecs to around 21, can still be improved, but at least the code is a bit simpler
Reviewers: #plasma
Subscribers: davidedmundson, plasma-devel, #frameworks
Tags: #plasma, #frameworks
Differential Revision: https://phabricator.kde.org/D4414
Revert the changes in contentsRect, it was clearly not the best place to
put the code that contains the code that computes the content size.
Instead move the code in FrameSvgItem, duplicates data and code but works.
