RenderSVGResource shouldn't trigger relayout during render tree teardown

MarkForLayoutOrParentResourceInvalidation can be called in SVG during
document teardown. This change skips that if the document is being
destroyed.

This is a merge of http://trac.webkit.org/changeset/155055 by
Andreas Kling <akling@apple.com>

BUG=285368

Review URL: https://chromiumcodereview.appspot.com/23531032

git-svn-id: svn://svn.chromium.org/blink/trunk@157428 bbb929c8-8fbe-4397-9dbb-9b2b20218538