Timeline: simplify handling of event category colors

third_party/WebKit/Source/devtools/front_end/timeline/timelinePanel.css

Index: third_party/WebKit/Source/devtools/front_end/timeline/timelinePanel.css
diff --git a/third_party/WebKit/Source/devtools/front_end/timeline/timelinePanel.css b/third_party/WebKit/Source/devtools/front_end/timeline/timelinePanel.css
index 9cdb8ed2c09706ae4c68d879908a55f2c95255f4..66f9302f4b394722f8cc8cd859248637e5957553 100644
--- a/third_party/WebKit/Source/devtools/front_end/timeline/timelinePanel.css
+++ b/third_party/WebKit/Source/devtools/front_end/timeline/timelinePanel.css
@@ -215,7 +215,7 @@
     margin: 0 6px;
     position: relative;
     top: 1px;
-    border: 1px solid;
+    border: 1px solid rgba(0, 0, 0, 0.2);
 }
 
 .popover ul {
@@ -378,6 +378,7 @@
 .timeline-details-chip-title > div {
     width: 12px;
     height: 12px;
+    border: 1px solid rgba(0, 0, 0, 0.2);
     display: inline-block;
     margin-right: 4px;
     content: " ";