[CrOS MultiDevice] Stop link click from opening subpage in Settings Page

In the HEAD version, a click on the Settings UI 'learn more' link will
route to the subpage when there is a set host (i.e. when waiting for
connection/verification) in addition to the intended behavior of
opening the subpage. This CL just adds a check to the
settings-multidevice-page's click handler that returns before routing
if the click target was a link.

Screenshot: http://screen/ka5Vd3vk1YC

Bug: 881375
Change-Id: I6c1c8e2ed2e6043d2f21442a0ce0b8e211da522e
Reviewed-on: https://chromium-review.googlesource.com/c/1259300Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Jordy Greenblatt <jordynass@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596394}

chrome/browser/resources/settings/multidevice_page/multidevice_feature_item.js

@@ -44,8 +44,10 @@ Polymer({
       return;
 
     // We do not navigate away if the click was on a link.
-    if (event.path[0].tagName === 'A')
+    if (event.path[0].tagName === 'A') {
+      event.stopPropagation();
       return;
+    }
 
     settings.navigateTo(this.subpageRoute);
   },

chrome/browser/resources/settings/multidevice_page/multidevice_page.js

@@ -183,7 +183,13 @@ Polymer({
   },
 
   /** @private */
-  handleItemClick_: function() {
+  handleItemClick_: function(event) {
+    // We do not open the subpage if the click was on a link.
+    if (event.path[0].tagName === 'A') {
+      event.stopPropagation();
+      return;
+    }
+
     if (!this.isHostSet())
       return;