Refactor tune() to pass in an integer-based count

Refactor tune() to pass in an integer-based count
https://bugs.webkit.org/show_bug.cgi?id=150060
<rdar://problem/23079425>

Reviewed by Dean Jackson.

All of the tune functions do an initial step of flooring the
# of painting objects to add or remove. Factor that out since
the complexity of all of these tests is always expressed in terms
of countable items.

* Animometer/tests/resources/main.js:
(Benchmark.prototype.update): Update the tuneValue.

* Animometer/tests/bouncing-particles/resources/bouncing-particles.js:
(BouncingParticlesStage.prototype.tune): Remove the count adjustment.
* Animometer/tests/examples/resources/canvas-electrons.js:
(CanvasElectronsStage.prototype.tune): Ditto.
* Animometer/tests/examples/resources/canvas-stars.js:
(CanvasStarsStage.prototype.tune): Ditto.
* Animometer/tests/text/resources/layering-text.js:
(LayeringTextStage.prototype.tune): Ditto.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@190908 268f45cc-cd09-0410-ab3c-d52691b4dbfc