Currently we only composite fixed position elements if we are on High DPI devices. This fix allows …

LayoutTests/compositing/layer-creation/fixed-position-under-transform.html

Index: LayoutTests/compositing/layer-creation/fixed-position-under-transform.html
diff --git a/LayoutTests/compositing/layer-creation/fixed-position-under-transform.html b/LayoutTests/compositing/layer-creation/fixed-position-under-transform.html
index 3e789f35421c1a9f5a68151f49a43e3eccf2bc59..07092c622687a5176e5e02989aaab05bc8dd56cb 100644
--- a/LayoutTests/compositing/layer-creation/fixed-position-under-transform.html
+++ b/LayoutTests/compositing/layer-creation/fixed-position-under-transform.html
@@ -16,7 +16,7 @@
     #indicator {
         width: 256px;
         height: 256px;
-        background-color: red;
+        background-color: rgba(255, 0, 0, 0.99);

[Ian Vollick, 2015/08/21 14:40:43]

Just to be sure I'm understanding you; you're changing these fixed pos elements
to not be opaque so that they test the same old behavior?

[davidfox, 2015/08/21 14:50:35]

That's exactly correct.

         position: fixed;
         left: 100px;
         top: 100px;
@@ -25,7 +25,7 @@
     #overlap {
         width: 500px;
         height: 500px;
-        background-color: green;
+        background-color: rgba(0, 128, 0, 0.99);
         position: fixed;
         left: 0px;
         top: 0px;