Change roots view to "rooted".

Instead of just showing roots in the roots view, show all objects
whose immediate dominator is the SENTINEL_ROOT.

Bug: 24613815
Change-Id: I96429d75395edfe109222e88d31cdc0bd87a7767
diff --git a/tools/ahat/src/ObjectHandler.java b/tools/ahat/src/ObjectHandler.java
index 9e4ce56..1305070 100644
--- a/tools/ahat/src/ObjectHandler.java
+++ b/tools/ahat/src/ObjectHandler.java
@@ -215,7 +215,7 @@
 
           public DocString render(Instance element) {
             if (element == null) {
-              return DocString.link(DocString.uri("roots"), DocString.text("ROOT"));
+              return DocString.link(DocString.uri("rooted"), DocString.text("ROOT"));
             } else {
               return DocString.text("→ ").append(Value.render(element));
             }