Update to latest rust-layers

We now need to pass through the content age of the LayerBuffer when
creating it.
Mark all layers as having changed content during pinch zoom

This ensures that layers know that they need to re-issue buffer
requests immediately instead of waiting until another content change
happens.

Fixes #2988.
Implement HTMLTableElement.caption
Merge pull request #3098 from wenderen/HTMLTableElement.caption

implement GetCaption and SetCaption for HTMLTableElement; r=Manishearth
Update rust-azure to fix a dangling pointer bug

Fixes #3084
Merge pull request #3102 from dotdash/fixup_azure_lifetime_bug

Update rust-azure to fix a dangling pointer bug
Merge pull request #3097 from mrobinson/pinch-zoom-delay

Update rust layers and fix delay in pinch zoom