DevTools: move timeline on tracing out of experimental

This patch makes Timeline panel use tracing backend by default. Should anything go wrong, the deprecated implementation can be reenabled using experimental setting. The setting will be removed along with the deprecated implementation once we collect enough feedback on the new implementation.

BUG=399531,361045

Review URL: https://codereview.chromium.org/597843002

git-svn-id: svn://svn.chromium.org/blink/trunk@183038 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Move resolveAlignment logic to RenderStyle

This CL moves resolveAlignment logic to RenderStyle as this seems
more appropriate place for this code. Also, the same logic is being
duplicated in both RenderGrid and RenderFlexible box, so it also
gets rid of duplicated code.

Review URL: https://codereview.chromium.org/547673002

git-svn-id: svn://svn.chromium.org/blink/trunk@183039 bbb929c8-8fbe-4397-9dbb-9b2b20218538