Add canvas line path tests

Add canvas line path tests
https://bugs.webkit.org/show_bug.cgi?id=150076
<rdar://problem/23082285>

Reviewed by Dean Jackson.

* Animometer/runner/resources/tests.js: Add new line path tests, with different
line joins.
* Animometer/tests/simple/resources/simple-canvas-paths.js:
(CanvasLinePathStage): The stage is the same as the SimpleCanvasPathStrokeStage
but sets the lineJoin on the context.
(CanvasPathBenchmark.prototype.createStage): Add the tests.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@190920 268f45cc-cd09-0410-ab3c-d52691b4dbfc