Welcome WebUI: Make step indicators pass color contrast

Bug: 1098534
Change-Id: I0aa61f1d64e384ab614f4dffc83ab48d654207c1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2324495Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: John Lee <johntlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#793371}

chrome/browser/resources/welcome/shared/navi_colors_css.html

@@ -14,8 +14,7 @@
       --navi-shape-red-color: rgb(233, 66, 53); /* #E94235 */
       --navi-shape-yellow-dots-color: rgb(253, 214, 99); /* #FDD663 */
       --navi-shape-yellow-semicircle-color: rgb(250, 207, 76); /* #FACF4C */
-      --navi-step-indicator-active-color:
-          rgba(var(--google-blue-600-rgb), .5);
+      --navi-step-indicator-active-color: var(--google-blue-600);
       --navi-step-indicator-color: var(--google-grey-200);
       --navi-wallpaper-text-color: var(--google-grey-refresh-700);
     }