chrome://flags Fix disappearing content in very tall absolute positioned

layer

Switched to a relative positioned container.

Bug: 777348
Change-Id: I4dd615d2ae067481536ca5106b598345868be27c
Reviewed-on: https://chromium-review.googlesource.com/744204Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Commit-Queue: Edward Jung <edwardjung@chromium.org>
Cr-Commit-Position: refs/heads/master@{#512800}

components/flags_ui/resources/flags.css

@@ -358,15 +358,16 @@ h2 {
 
 .tab-content {
   display: none;
-  left: 0;
   line-height: 25px;
+  margin-top: -50px;
   /* Bottom padding should be greater than evaluated height of needs-restart */
   padding-bottom: 200px;
-  padding-top: 24px;
-  position: absolute;
-  top: -25px;
-  width: 100%;
-  z-index: 0;
+  position: relative;
+  width: 200%;
+}
+
+.tabs li:nth-child(2) .tab-content {
+  margin-left: -100%;
 }
 
 .selected .tab-content {