Attempt to fix win7 about flags relaunch rendering.

I do not have a win7 machine, so I'm assuming the issue is with
rounding of some sort.

Setting to more standard sizing (700 for weight to match bold) and
removing the font-size declaration as it was not really needed.

Also added a drop shadow above the relaunch bar...for flair!

BUG=487597

Review URL: https://codereview.chromium.org/1135423002

Cr-Commit-Position: refs/heads/master@{#329689}

chrome/browser/resources/flags.css

@@ -169,6 +169,7 @@ div.needs-restart {
   background: #FFF;
   border-top: 1px solid rgb(181, 199, 222);
   bottom: 0;
+  box-shadow: 0 -2px 2px #ddd;
   box-sizing: border-box;
   left: 0;
   padding-bottom: 15px;
@@ -187,8 +188,7 @@ div.needs-restart {
   box-sizing: border-box;
   color: #fff;
   cursor: pointer;
-  font-size: .875em;
-  font-weight: 600;
+  font-weight: 700;
   margin-top: 10px;
   padding: 10px 24px;
   text-transform: uppercase;