better styling for deprecated api items (angular#384)

* Adds a dotted underline to the `Deprecated` markers. Those can be hovered to see more information about the deprecation / deletion.
* Fixes that the deprecation markers are too big and are not looking good in the API table
* Adds a line through property names that are also deprecated. This makes it clear that this API is deprecated and also looks pretty good.

References angular#9648

src/app/pages/component-viewer/component-api.scss

@@ -34,10 +34,6 @@
   line-height: 24px;
 }
 
-.docs-api-class-deprecated-marker {
-  font-weight: bold;
-}
-
 .docs-api-property-type {
   font-weight: bold;
   font-size: 14px;

src/styles/_api.scss

@@ -56,7 +56,8 @@
 }
 
 .docs-api-input-marker,
-.docs-api-output-marker {
+.docs-api-output-marker,
+.docs-api-deprecated-marker {
   // Size corresponding to "caption"-style text in the spec.
   font-size: 12px;
 }
@@ -67,3 +68,19 @@
   font-family: 'Roboto Mono', monospace;
   padding: 3px;
 }
+
+.docs-api-deprecated-marker,
+.docs-api-class-deprecated-marker,
+.docs-api-interface-deprecated-marker {
+  display: inline-block;
+  font-weight: bold;
+
+  &[title] {
+    border-bottom: 1px dotted grey;
+    cursor: help;
+  }
+}
+
+.docs-api-deprecated-marker + .docs-api-property-name {
+  text-decoration: line-through;
+}