Add attribute event listeners to visualViewport

These were previously available but removed in r407955. In the mean time
they made their way into the visualViewport draft spec:

But we forgot to actually re-add them. This patch adds them back in.

(cherry picked from commit c3d1b5db2b08e3762fb9aab3d82ad5d6ff799103)

Bug: 760916
Change-Id: Ib2dc3dbd21d648d9118bbb88e61bba7b65369688
Reviewed-by: Dave Tapuska <>
Reviewed-by: Kent Tamura <>
Commit-Queue: David Bokan <>
Cr-Original-Commit-Position: refs/heads/master@{#501855}
Reviewed-by: David Bokan <>
Cr-Commit-Position: refs/branch-heads/3202@{#435}
Cr-Branched-From: fa6a5d87adff761bc16afc5498c3f5944c1daa68-refs/heads/master@{#499098}
13 files changed