Devtools [CustomFormatters]: Fix appearance of an arrow on the mac

Source/devtools/front_end/components/customPreviewSection.css

Index: Source/devtools/front_end/components/customPreviewSection.css
diff --git a/Source/devtools/front_end/components/customPreviewSection.css b/Source/devtools/front_end/components/customPreviewSection.css
index a1a7629c7adca56f537e246bc2017f2e9adf0ee7..96a7e461c24529b189bc0371a128c62722d7073a 100644
--- a/Source/devtools/front_end/components/customPreviewSection.css
+++ b/Source/devtools/front_end/components/customPreviewSection.css
@@ -22,6 +22,13 @@
     text-shadow: none;
 }
 
+@media (-webkit-min-device-pixel-ratio: 1.5) {
+    .custom-expandable-section-header::before {
+        background-image: url(Images/toolbarButtonGlyphs_2x.png);
+    }
+} /* media */
+
+
 .custom-expandable-section-header::before {
     background-position: -4px -96px;
 }