Add anchor support to hittest sample

[lehoangphu]

Anchor are mostly leveraged together with the hit-test. Thus, we should update the hittest sample to demonstrate the usage of Anchor and Hit-test together.

[lehoangphu]

Agree. I put back hit-test.html and keep it together with the new hit-test-anchors.html

[lehoangphu]

Thank you for the feedbacks. I have updated the title and description to better reflect the change.

[toji]

Thank you!