Chrome OS OOBE - Fix arrows for RTL languages

Changes the direction of arrows on Chrome OS OOBE for RTL languages.
OOBE Back and Next buttons now show the expected direction.

Tested locally.

Bug: 1016376
Change-Id: I8a00e900f9b3c02c9bca69a8f98d9c8a72244dbc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1929829Reviewed-by: Denis Kuznetsov [CET] <antrim@chromium.org>
Commit-Queue: Renato Silva <rrsilva@google.com>
Cr-Commit-Position: refs/heads/master@{#718593}

chrome/browser/resources/chromeos/login/oobe_back_button.css

@@ -7,7 +7,11 @@ cr-button {
   padding-inline-start: 8px;
 }
 
-hd-iron-icon {
+:host-context([dir=ltr]) hd-iron-icon {
   padding-inline-start: 4px; /* transform(180deg) will make it inline-end. */
   transform: rotate(180deg);
 }
+
+:host-context([dir=rtl]) hd-iron-icon {
+  padding-inline-end: 4px;
+}

chrome/browser/resources/chromeos/login/oobe_next_button.css

@@ -7,6 +7,11 @@ cr-button {
   padding-inline-start: 16px;
 }
 
-hd-iron-icon {
+:host-context([dir=ltr]) hd-iron-icon {
   padding-inline-start: 4px;
 }
+
+:host-context([dir=rtl]) hd-iron-icon {
+  padding-inline-end: 4px;
+  transform: rotate(180deg);
+}