Week 17 updates on QtWebKit stable branches (v2.1.x)

Release Notes for qtwebkit-2.1.x-week17 - Changes since qtwebkit-2.1.x-week16
2 bugs, 2 commits

Bugs fixed / Tasks done:

• #46259: [Qt] QNetworkReplyHandler forces buffered output for FormData with files
  
• #56393: Without checking existence of the renderer of the element,tries to access the enclosing layer.

Commits added or cherry-picked:

• c56e63a: Fix crash when trying to access the enclosing layer without a renderer
  
• 2bb9aaf: [Qt] QNetworkReplyHandler forces buffered output for FormData with files