Modify LayoutTests to prep for compositing solid background scollers

third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent.html

Index: third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent.html
diff --git a/third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent.html b/third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent.html
index 262affad9959aaea281bf7aea35c21c415c331e2..667b3292d7c3faaca765498b458e7d082c43ad6d 100644
--- a/third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent.html
+++ b/third_party/WebKit/LayoutTests/compositing/overflow/clear-scroll-parent.html
@@ -8,6 +8,7 @@
         border: 4px solid black;
         overflow-y: scroll;
         resize: both;
+        background-color: rgba(0,0,255,0.5);

[flackr, 2016/08/02 15:02:44]

It looks like .container had a transparent background before, so we don't need
to give it a background do we?

[Stephen Chennney, 2016/08/02 19:00:00]

I added this to make sure that we also paint the container background. I'll make
it green though.

     }
 
     .box {
@@ -16,7 +17,7 @@
         height: 100px;
         width: 100px;
         margin: 10px;
-        background-color: blue;
+        background-color: rgba(0,0,255,0.5);
     }
 
 
@@ -31,7 +32,7 @@
     }
 
     .red {
-        background-color: red;
+        background-color: rgba(255,0,0,0.5);
     }
 
     .clip {