QmlDesigner: Remove workaround

Because we can now commit a invalid transaction so we don't need to create
a new transaction.

Change-Id: I91bcd403d6a5a73df1c1b0b74f06eb3ff7423caa
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Add RewriterTransaction tracing framework

Change-Id: I6c152e128e0a1b1d4450bbba81e47d072aac3038
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlDesigner: Fix crash in anchor update function

Task-number: QTCREATORBUG-11138
Change-Id: Ie7eeb1cf93d96f377f53cb69587285c8da7988a7
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>