[WebUI] Fix all CSS nits in chrome/browser/resources/chromeos.

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

Index: chrome/browser/resources/chromeos/login/bubble.css
diff --git a/chrome/browser/resources/chromeos/login/bubble.css b/chrome/browser/resources/chromeos/login/bubble.css
index 89163f65135b498f1ce2358b7f8572d36415d324..d346bdb6eb894feecfb67f6864d3c04dc8b92665 100644
--- a/chrome/browser/resources/chromeos/login/bubble.css
+++ b/chrome/browser/resources/chromeos/login/bubble.css
@@ -6,20 +6,20 @@
  */
 
 .bubble {
-  -webkit-box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
   background: white;
   border: 1px solid rgba(0, 0, 0, 0.25);
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
   font-size: 12px;
   margin: 2px;
+  max-width: 250px;
   padding: 16px;
   position: absolute;
-  max-width: 250px;
 }
 
 .bubble:before {
-  content: "";
   border-style: solid;
   border-width: 8px;
+  content: '';
   display: block;
   position: absolute;
 }
@@ -65,9 +65,9 @@ html[dir=rtl] .bubble-right:before {
 }
 
 .bubble:after {
-  content: "";
   border-style: solid;
   border-width: 8px;
+  content: '';
   display: block;
   position: absolute;
 }