Selection highlight size always based on the first layer style

[morkl]

When a point layer has multiple layer styles, the size of the selection highlight is based on the first one, not the one that matches the current scale.

This is a problem when the first style is defined with map space sizes (e.g. 1x1 m) and the subsequent ones with device space sizes (e.g. 5x5 mm), since the highlights are barely visible at small scales.

See attached images (three features on the right are selected).

[morkl]

three features selected; highlight barely visible

[morkl]

same view, no selection

[jng]

Fixed r7281