DevTools: fix network waterfall sorting icon

This patch:
- hides network waterfall sorting icon if other column is used for sorting
- makes icon crisp on retina

BUG=684894
R=dgozman, allada

Review-Url: https://codereview.chromium.org/2652893008
Cr-Commit-Position: refs/heads/master@{#445921}

front_end/network/NetworkLogViewColumns.js

@@ -263,9 +263,9 @@ Network.NetworkLogViewColumns = class {
     var columnId = this._dataGrid.sortColumnId();
     this._networkLogView.removeAllNodeHighlights();
     this._waterfallRequestsAreStale = true;
-    if (columnId === 'waterfall') {
-      this._waterfallColumnSortIcon.classList.remove('sort-ascending', 'sort-descending');
+    this._waterfallColumnSortIcon.classList.remove('sort-ascending', 'sort-descending');
 
+    if (columnId === 'waterfall') {
       if (this._dataGrid.sortOrder() === DataGrid.DataGrid.Order.Ascending)
         this._waterfallColumnSortIcon.classList.add('sort-ascending');
       else

front_end/network/networkLogView.css

@@ -389,6 +389,12 @@
     display: none;
 }
 
+@media (-webkit-min-device-pixel-ratio: 1.1) {
+.network-waterfall-header .sort-order-icon {
+    background-image: url(Images/toolbarButtonGlyphs_2x.png);
+}
+} /* media */
+
 .network-waterfall-header .sort-ascending.sort-order-icon {
     display: block;
     background-position: -4px -111px;