Apply "type inference for generic instance creation" Java 7 feature

Since GWT 2.6.0 support for Java 7 is added. Simplify creation of
classes in GWT's client code.

Change-Id: I08ff2c189d2874a6b957072912912e4a6089cdd1

gerrit-gwtui/src/main/java/com/google/gerrit/client/ui/AccountSuggestOracle.java

@@ -34,7 +34,7 @@ public class AccountSuggestOracle extends SuggestAfterTypingNCharsOracle {
             new GerritCallback<List<AccountInfo>>() {
               public void onSuccess(final List<AccountInfo> result) {
                 final ArrayList<AccountSuggestion> r =
-                    new ArrayList<AccountSuggestion>(result.size());
+                    new ArrayList<>(result.size());
                 for (final AccountInfo p : result) {
                   r.add(new AccountSuggestion(p));
                 }