Change default style sheet for forms in quirks mode in vertical writing-mode.

This change matches the behavior of Edge, Firefox and the spec:
https://html.spec.whatwg.org/multipage/rendering.html#flow-content-3

Bug: 612424
Change-Id: Ib085301f732b259f2789d50b92aff9e12dcf4ae7
Reviewed-on: https://chromium-review.googlesource.com/1254724Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Dominik Röttsches <drott@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595815}

AUTHORS

@@ -116,6 +116,7 @@ Bernhard M. Wiedemann <bwiedemann@suse.de>
 Bhagirathi Satpathy <bhagirathi.s@samsung.com>
 Bhanukrushana Rout <b.rout@samsung.com>
 Biljith Jayan <billy.jayan@samsung.com>
+Boaz Sender <boaz@bocoup.com>
 Bobby Powers <bobbypowers@gmail.com>
 Branden Archer <bma4@zips.uakron.edu>
 Brendan Kirby <brendan.kirby@imgtec.com>
@@ -969,6 +970,7 @@ ACCESS CO., LTD. <*@access-company.com>
 Akamai Inc. <*@akamai.com>
 ARM Holdings <*@arm.com>
 BlackBerry Limited <*@blackberry.com>
+Bocoup <*@bocoup.com>
 Canonical Limited <*@canonical.com>
 Cloudflare, Inc. <*@cloudflare.com>
 Code Aurora Forum <*@codeaurora.org>

third_party/WebKit/LayoutTests/external/wpt/html/rendering/non-replaced-elements/flow-content-0/form-margin-quirk-expected.txt

-This is a testharness.js-based test.
-FAIL form margin quirk assert_equals: marginRight expected "16px" but got "0px"
-Harness: the test ran to completion.
-

third_party/blink/renderer/core/css/quirks.css

@@ -50,5 +50,5 @@ input:not([type=image i]), textarea {
 /* Set margin-bottom for form element in quirks mode. */
 /* Compatible with Gecko. (Doing this only for quirks mode is a fix for bug 17696.) */
 form {
-    margin-bottom: 1em
+    margin-block-end: 1em
 }