Remove style invalidation trace events in preparation for new ones

This patch removes the style invalidation trace events added in [1]
in preparation for new invalidation trace events being added as part
of crbug.com/410701. These invalidation trace events were useful
but are not currently being used.

[1] https://src.chromium.org/viewvc/blink?view=rev&revision=163916

BUG=410701

Review URL: https://codereview.chromium.org/544533002

git-svn-id: svn://svn.chromium.org/blink/trunk@182859 bbb929c8-8fbe-4397-9dbb-9b2b20218538