DevTools: set a default color for icon masks

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

Index: third_party/WebKit/Source/devtools/front_end/ui/inspectorCommon.css
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/inspectorCommon.css b/third_party/WebKit/Source/devtools/front_end/ui/inspectorCommon.css
index cedc661e43f7ac95a8d4699cf0022870c4a2c57a..f0fb819a45ab992e034c519cd6c2231e601c0f59 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/inspectorCommon.css
+++ b/third_party/WebKit/Source/devtools/front_end/ui/inspectorCommon.css
@@ -327,6 +327,10 @@ label[is=dt-icon-label] {
     flex-shrink: 0;
 }
 
+.icon-mask {
+    background-color: rgb(110, 110, 110);
+}
+
 .spritesheet-smallicons {
     background-image: -webkit-image-set(url(Images/smallIcons.png) 1x, url(Images/smallIcons_2x.png) 2x);
     background-size: 190px 30px;