Remove updateLayoutTreeIfNeeded from SVGElement::invalidateInstances

There is no need to update the layout tree when instances are
invalidated. This fixes an O(n^2) performance bug when updating
<use> trees.

BUG=565120

Review URL: https://codereview.chromium.org/1498323002

Cr-Commit-Position: refs/heads/master@{#363393}
1 file changed