DevTools: migrate UI.ListWidget icons over to UI.Icon

third_party/WebKit/Source/devtools/front_end/ui/listWidget.css

Index: third_party/WebKit/Source/devtools/front_end/ui/listWidget.css
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/listWidget.css b/third_party/WebKit/Source/devtools/front_end/ui/listWidget.css
index 6062ab735abb0d043e2da990d35920c7bfd62b5b..505101988a7218af22def6cf5b7ab147b16a392f 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/listWidget.css
+++ b/third_party/WebKit/Source/devtools/front_end/ui/listWidget.css
@@ -58,23 +58,12 @@
 
 .remove-button,
 .edit-button {
-    background-image: url(Images/toolbarButtonGlyphs.png);
-    background-size: 352px 168px;
-    width: 32px;
-    height: 24px;
     opacity: 0.5;
     cursor: pointer;
     flex: none;
     visibility: hidden;
 }
 
-@media (-webkit-min-device-pixel-ratio: 1.1) {
-.remove-button,
-.edit-button {
-    background-image: url(Images/toolbarButtonGlyphs_2x.png);
-}
-} /* media */
-
 .list-item:hover .remove-button,
 .list-item:hover .edit-button {
     visibility: visible;