[PhraseAndIterator] Remove temporary arrays when checking matches

Summary:
Instead of copying all positions and applying the the shift on the
copies, apply the shift when comparing the positions.

Reviewers: Baloo, ngraham

Reviewed By: Baloo, ngraham

Subscribers: kde-frameworks-devel

Tags: Frameworks, Baloo

Differential Revision: https://phabricator.kde.org/D28865