cc: Workaround invalid property tree state on Layers.

The impl thread is somehow getting Layers with invalid property tree
indices which cause crashes during UpdateDrawProperties. Don't add them
to the visible layer list to keep from crashing later in the stack.

BUG=728511, 727209, 726423
CQ_INCLUDE_TRYBOTS=master.tryserver.blink:linux_trusty_blink_rel

Review-Url: https://codereview.chromium.org/2918163002
Cr-Commit-Position: refs/heads/master@{#476811}
3 files changed