Clarify presentation of the target in retaining paths.

runtime/observatory/lib/src/elements/css/shared.css

 /* Global styles */
 * {
   margin: 0;
   padding: 0;
   box-sizing: border-box;
 }
 
 body {
   padding-top: 56px;
   color: #333;
@@ skipping 549 matching lines @@
 
 /* code-ref */
 
 code-ref > a[href]:hover {
   text-decoration: underline;
 }
 code-ref > a[href] {
   color: #0489c3;
   text-decoration: none;
 }
+code-ref .emphasize {
+  font-style: italic;
+}
+
 
 /* class-tree */
 
 class-tree {
   position: relative;
   display: block;
   height: 100%;
 }
 
 class-tree virtual-tree {
@@ skipping 60 matching lines @@
 }
 
 code-view .code-comment {
   color: grey;
   font-style: italic;
 }
 
 /* context-ref */
 
 context-ref > a[href]:hover {
-    text-decoration: underline;
+  text-decoration: underline;
 }
 context-ref > a[href] {
-    color: #0489c3;
-    text-decoration: none;
+  color: #0489c3;
+  text-decoration: none;
 }
 context-ref > a[href] * {
-    color: inherit;
+  color: inherit;
 }
+context-ref .emphasize {
+  font-style: italic;
+}
+
 
 /* cpu-profile */
 
 cpu-profile {
   position: relative;
   display: block;
   height: 100%;
 }
 
 cpu-profile > cpu-profile-virtual-tree {
@@ skipping 576 matching lines @@
 
 /* function-ref */
 
 function-ref > a[href]:hover {
   text-decoration: underline;
 }
 function-ref > a[href] {
   color: #0489c3;
   text-decoration: none;
 }
+function-ref .emphasize {
+  font-style: italic;
+}
+
 
 /* heap-snapshot */
 
 heap-snapshot .statusMessage {
   font-size: 150%;
   font-weight: bold;
 }
 heap-snapshot .statusBox {
   height: 100%;
   padding: 1em;
@@ skipping 33 matching lines @@
 
 heap-snapshot .tree-item > .name {
   display: inline;
   margin-left: 0.5em;
 }
 
 
 /* icdata-ref */
 
 icdata-ref > a[href]:hover {
-    text-decoration: underline;
+  text-decoration: underline;
+}
+icdata-ref > a[href] {
+  color: #0489c3;
+  text-decoration: none;
+}
+icdata-ref > a[href] * {
+  color: inherit;
+}
+icdata-ref .emphasize {
+  font-style: italic;
 }
 
-icdata-ref > a[href] {
-    color: #0489c3;
-    text-decoration: none;
-}
-
-icdata-ref > a[href] * {
-    color: inherit;
-}
 
 /* inbound-reference */
 
 inbound-reference > a[href]:hover {
   text-decoration: underline;
 }
 inbound-reference > a[href] {
   color: #0489c3;
   text-decoration: none;
 }
@@ skipping 148 matching lines @@
 
 /* library-ref */
 
 library-ref > a[href]:hover {
   text-decoration: underline;
 }
 library-ref > a[href] {
   color: #0489c3;
   text-decoration: none;
 }
+library-ref .emphasize {
+  font-style: italic;
+}
+
 
 .nav-option {
   float: right;
   margin: 3px;
   padding: 8px;
 }
 
 .nav-option label {
   color: white;
 }
@@ skipping 51 matching lines @@
 megamorphic-cache-ref > a[href]:hover {
     text-decoration: underline;
 }
 megamorphic-cache-ref > a[href] {
     color: #0489c3;
     text-decoration: none;
 }
 megamorphic-cache-ref > a[href] * {
     color: inherit;
 }
+megamorphic-ref .emphasize {
+  font-style: italic;
+}
 
 /* metric-graph */
 
 metric-graph {
   display: block;
   height: 100%;
 }
 
 metric-graph .graph {
   height: 100%;
@@ skipping 234 matching lines @@
   color: #0489c3;
   padding: 0;
   margin: -8px 4px;
   font-size: 20px;
   text-decoration: none;
 }
 
 /* object-pool-ref */
 
 object-pool-ref > a[href]:hover {
-    text-decoration: underline;
+  text-decoration: underline;
 }
 
 object-pool-ref > a[href] {
-    color: #0489c3;
-    text-decoration: none;
+  color: #0489c3;
+  text-decoration: none;
 }
-
 object-pool-ref > a[href] * {
-    color: inherit;
+  color: inherit;
+}
+object-pool-ref .emphasize {
+  font-style: italic;
 }
 
 /* object-pool-view */
 
 object-pool-view .hexadecimal {
   font-family: monospace;
 }
 
 /* observatory-application */
 
@@ skipping 72 matching lines @@
 
 /* ports-page */
 
 ports-page .port-number {
   font-weight: bold;
 }
 
 /* script-ref */
 
 script-ref > a[href]:hover {
-    text-decoration: underline;
+  text-decoration: underline;
+}
+script-ref > a[href] {
+  color: #0489c3;
+  text-decoration: none;
+}
+script-ref .emphasize {
+  font-style: italic;
 }
 
-script-ref > a[href] {
-    color: #0489c3;
-    text-decoration: none;
-}
 
 /* source-link */
 
 source-link > a[href]:hover {
     text-decoration: underline;
 }
 
 source-link > a[href] {
     color: #0489c3;
     text-decoration: none;
@@ skipping 233 matching lines @@
 
 /* type-arguments-ref */
 
 type-arguments-ref a[href]:hover {
   text-decoration: underline;
 }
 type-arguments-ref a[href] {
   color: #0489c3;
   text-decoration: none;
 }
+type-arguments-ref .emphasize {
+  font-style: italic;
+}
+
 
 /* token-stream-ref */
 
 token-stream-ref a[href]:hover {
   text-decoration: underline;
 }
 token-stream-ref a[href] {
   color: #0489c3;
   text-decoration: none;
 }
+token-stream-ref .emphasize {
+  font-style: italic;
+}
+
+
+/* unknown-ref */
+
+unknown-ref > a[href]:hover {
+  text-decoration: underline;
+}
+unknown-ref > a[href] {
+  color: #0489c3;
+  text-decoration: none;
+}
+unknown-ref > a[href] * {
+  color: inherit;
+}
+unknown-ref .emphasize {
+  font-style: italic;
+}
+
 
 /* view-footer */
 
 view-footer {
   padding: 1em;
   padding-top: 10.3em;
   float: right;
   align-content: right;
 }
 
@@ skipping 111 matching lines @@
 
 vm-connect-target > button.delete-button:hover {
   background: #ff0000;
 }
 
 /* vm-connect */
 
 vm-connect ul {
   list-style-type: none;
 }