DevTools: migrate elements panel gutter icon to UI.Icon

third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.css

Index: third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.css
diff --git a/third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.css b/third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.css
index 72a14ef848a25fb16276355a2f3667771efdfe60..b7b85bfba95d208f9985a615aa35895e1ae2b363 100644
--- a/third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.css
+++ b/third_party/WebKit/Source/devtools/front_end/elements/elementsTreeOutline.css
@@ -321,26 +321,22 @@ ol:focus li.selected .webkit-html-attribute-name {
 .elements-disclosure .gutter-container {
     position: absolute;
     top: 0;
+    left: 0;
+    cursor: pointer;
 }
 
-.elements-disclosure li.selected .gutter-container:not(.has-decorations) {
-    left: 0px;
-    width: 16.25px;
-    height: 18px;
-    transform: rotate(-90deg) translateX(-13px) scale(0.8);
-    transform-origin: 0% 0%;
-    -webkit-mask-image: url(Images/toolbarButtonGlyphs.png);
-    -webkit-mask-position: -201px -27px;
-    -webkit-mask-size: 352px 168px;
+.gutter-menu-icon {
+    display: none;
+    transform: rotate(-90deg) scale(0.8);
     background-color: white;
-    cursor: pointer;
+    position: relative;
+    left: -7px;
+    top: -3px;
 }
 
-@media (-webkit-min-device-pixel-ratio: 1.1) {
-.elements-disclosure li.selected .gutter-container:not(.has-decorations) {
-    -webkit-mask-image: url(Images/toolbarButtonGlyphs_2x.png);
+.elements-disclosure li.selected .gutter-container:not(.has-decorations) .gutter-menu-icon {
+    display: block;
 }
-} /* media */
 
 /** Guide line */
 li.selected {