Enable ZoomAndPan in an "SVG document" without an <svg> document element

Disabling zoom and pan in this (odd special-)case leads to some weird
behavior, so just enable it instead to avoid confusion.

This takes care of one of the testcases mentioned in the referenced bug,
but does not address the real issue in any way.

Bug: 222786
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I25d9cbf9cd10c1631d64fddcd133014b9602bcba
Reviewed-on: https://chromium-review.googlesource.com/c/1275886
Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#598756}
3 files changed