GitLab

Fix a couple of issues related to handling of some types of
invisible elements:
* When element.getClientRects() returns an empty list, the code tries to
  use getBoundingClientRect, but the Object.assign call doesn't work
  correctly.
* Zero-size elements can't be clicked on. Return appropriate error.

These changes fix problems reported in an internal Google discussion
(https://groups.google.com/a/google.com/g/webdriver-users/c/CKv3HQCBA4o).

Change-Id: I4f9a2c42e6268441b6b3105de23bbef7b370a0c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079998
Commit-Queue: John Chen <johnchen@chromium.org>
Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Auto-Submit: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745529}