QmlEditorWidgets: Pass QVariant as const reference

Change-Id: Ib59cb25ffed6acc4f1ad6dd450b68dc30372b168
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlEditorWidgets: Avoid repetitive calls

Change-Id: If574ad37fa25ced45a86ee0721da0e97c2845dc6
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>
QmlJS: Fix wrong conditions

Change-Id: I31740bca2b17e635c28af70779334f2b52ddb709
Reviewed-by: Fawzi Mohamed <fawzi.mohamed@digia.com>
Core: Pass const values by reference

Change-Id: I44f16528f2ee8fb41351153bab8dc340f4f2cca1
Reviewed-by: hjk <hjk121@nokiamail.com>