Restore outline on focus for security warnings

When tab focus is placed on the security warning primary button, Chrome
should outline the button. However, the outline is not shown during
button activation to prevent it from making the button border an odd
white-gray-blue.

BUG=387163
R=bauerb@chromium.org

Review URL: https://codereview.chromium.org/511073002

Cr-Commit-Position: refs/heads/master@{#292384}

chrome/browser/resources/security_warnings/interstitial_v2.css

@@ -28,7 +28,6 @@ button {
   font-size: .875em;
   height: 36px;
   margin: -6px 0 0;
-  outline: 0;
   padding: 8px 24px;
   transition: box-shadow 200ms cubic-bezier(0.4, 0, 0.2, 1);
 }
@@ -39,6 +38,7 @@ button {
 
 button:active {
   background: rgb(50, 102, 213);
+  outline: 0;
 }
 
 button:hover {
@@ -197,11 +197,6 @@ input[type=checkbox] {
   opacity: 1;
 }
 
-.yellow :-webkit-any(
-    a, #details, #details-button, h1, .small-link) {
-  color: black;
-}
-
 @media (max-width: 700px) {
   .interstitial-wrapper {
     padding: 0 10%;