Add search autocompletion for 'assignee' and 'is:assigned'

Bug: Issue 5935
Change-Id: I1ac756bc323abd9e15a7f8b38342daff57d6d431
(cherry picked from commit 0ecc845e439b245e609c7f249d462fdae1cd56f5)
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/SearchSuggestOracle.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/SearchSuggestOracle.java
index e46ba72..cb3e9f0 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/SearchSuggestOracle.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/SearchSuggestOracle.java
@@ -89,6 +89,7 @@
     suggestions.add("ownerin:");
     suggestions.add("author:");
     suggestions.add("committer:");
+    suggestions.add("assignee:");
 
     suggestions.add("reviewer:");
     suggestions.add("reviewer:self");
@@ -136,6 +137,7 @@
     suggestions.add("is:mergeable");
     suggestions.add("is:ignored");
     suggestions.add("is:wip");
+    suggestions.add("is:assigned");
 
     suggestions.add("status:");
     suggestions.add("status:open");
diff --git a/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.js b/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.js
index ba7aad3..553eacf 100644
--- a/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.js
+++ b/polygerrit-ui/app/elements/core/gr-search-bar/gr-search-bar.js
@@ -19,6 +19,7 @@
     'added:',
     'age:',
     'age:1week', // Give an example age
+    'assignee:',
     'author:',
     'branch:',
     'bug:',
@@ -44,6 +45,7 @@
     'intopic:',
     'is:',
     'is:abandoned',
+    'is:assigned',
     'is:closed',
     'is:ignored',
     'is:mergeable',