DevTools: fixed UI glitches of inlined DataGrid.

Source/devtools/front_end/dataGrid.css

Index: Source/devtools/front_end/dataGrid.css
diff --git a/Source/devtools/front_end/dataGrid.css b/Source/devtools/front_end/dataGrid.css
index b6cda5ca23b5f4f68d40208138f5ccc24402182b..c403a3fd495325ce0019056632919450af63e7af 100644
--- a/Source/devtools/front_end/dataGrid.css
+++ b/Source/devtools/front_end/dataGrid.css
@@ -39,6 +39,7 @@
     position: static;
 }
 
+.data-grid.inline col.corner,
 .data-grid.inline th.corner,
 .data-grid.inline td.corner {
     display: none;
@@ -98,8 +99,8 @@
     border-left: 1px solid #aaa;
 }
 
-.data-grid th:first-child,
-.data-grid td:first-child {
+.data-grid:not(.inline) th:first-child,
+.data-grid:not(.inline) td:first-child {
     border-left: none !important;
 }