Add aria-hidden state to layout panel rulers.

Contributed by tbroyer
Fixes issues 7646
Review at: https://gwt-code-reviews.appspot.com/1820807/

Review by: cromwellian@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@11263 8db76d5a-ed1c-0410-87a9-c151d255dfc7

user/src/com/google/gwt/layout/Layout.gwt.xml

diff --git a/user/src/com/google/gwt/layout/Layout.gwt.xml b/user/src/com/google/gwt/layout/Layout.gwt.xml
index 65797b5..c7a22f5 100644
--- a/user/src/com/google/gwt/layout/Layout.gwt.xml
+++ b/user/src/com/google/gwt/layout/Layout.gwt.xml
@@ -14,9 +14,12 @@
 
 <module>
   <inherits name="com.google.gwt.core.Core"/>
-  <inherits name="com.google.gwt.user.UserAgent"/>
+  <inherits name="com.google.gwt.useragent.UserAgent"/>
   <inherits name="com.google.gwt.dom.DOM"/>
   <inherits name="com.google.gwt.animation.Animation"/>
+  <inherits name="com.google.gwt.aria.Aria"/>
+  <!--  LayoutImplIE6 uses c.g.g.u.c.Window -->
+  <inherits name="com.google.gwt.user.Window"/>
 
   <replace-with class="com.google.gwt.layout.client.LayoutImplIE8">
     <when-type-is class="com.google.gwt.layout.client.LayoutImpl"/>

user/src/com/google/gwt/layout/client/LayoutImpl.java

diff --git a/user/src/com/google/gwt/layout/client/LayoutImpl.java b/user/src/com/google/gwt/layout/client/LayoutImpl.java
index a21f3f7..9816333 100644
--- a/user/src/com/google/gwt/layout/client/LayoutImpl.java
+++ b/user/src/com/google/gwt/layout/client/LayoutImpl.java
@@ -19,6 +19,7 @@
 import static com.google.gwt.dom.client.Style.Unit.EX;
 import static com.google.gwt.dom.client.Style.Unit.PX;
 
+import com.google.gwt.aria.client.State;
 import com.google.gwt.dom.client.DivElement;
 import com.google.gwt.dom.client.Document;
 import com.google.gwt.dom.client.Element;
@@ -62,6 +63,8 @@
     // extra precision.
     style.setWidth(10, widthUnit);
     style.setHeight(10, heightUnit);
+
+    State.HIDDEN.set(ruler, true);
     return ruler;
   }