QmlProfiler: Remove some dead code and make sizing more consistent.

Change-Id: Iaff416c1af61e20e47309b7ec34bf4ab0d3f4267
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
QmlProfiler: Reduce code duplication and add more anchoring

Anchors are supposed to reduce graphical glitches such as the gradient
borders getting detached from the edges of the timeline while resizing.
I'm not sure if it's actually better like this, but the code certainly
looks nicer.

Change-Id: I9eb6a6a50780ce642ad7cb551d2895a80b00690e
Reviewed-by: Kai Koehne <kai.koehne@digia.com>