Fix tests

gwtquery-core/src/main/java/com/google/gwt/query/client/GQuery.java

         return $(JsUtils.<Element> cast(o));
       }
       if (o instanceof JsonBuilder) {
-        return new GQuery(((JsonBuilder) o).getDataImpl());
+        return new GQuery(((JsonBuilder) o).<Element>getDataImpl());
       }
       if (o instanceof JavaScriptObject) {
         return $((JavaScriptObject) o);

gwtquery-core/src/main/java/com/google/gwt/query/client/plugins/ajax/Ajax.java

   }
 
   public static Promise loadScript(final String url, Function success) {
-    GQuery script = $("script[src^='" + url + "']");
-    if (script.isEmpty()) {
+    if (!GWT.isClient() || $("script[src^='" + url + "']").isEmpty()) {
       return ajax(createSettings()
           .setUrl(url)
           .setType("get")
     return this;
   }
 
-  public static Promise loadLink(String rel, String url) {
+  public static Promise loadLink(final String rel, final String url) {
     GQuery link = $("link[rel='" + rel + "'][href^='" + url + "']");
     if (link.isEmpty()) {
       return new PromiseFunction() {
-        public void f(Deferred dfd) {
+        public void f(final Deferred dfd) {
           GQuery link = $("<link rel='" + rel + "' href='" + url + "'/>");
           link.on("load", new Function() {
             public void f() {

gwtquery-core/src/test/java/com/google/gwt/query/client/GQueryCoreTestGwt.java

   public void testPropMethod(){
     $(e).html("<input id=\"checkBox1\" type=\"checkbox\" checked=\"checked\" /> <input id=\"checkBox2\" type=\"checkbox\" />");
 
-    assertEquals(true, $("#checkBox1",e).prop("checked"));
-    assertEquals(false, $("#checkBox2",e).prop("checked"));
+    assertEquals(Boolean.TRUE, $("#checkBox1",e).prop("checked"));
+    assertEquals(Boolean.FALSE, $("#checkBox2",e).prop("checked"));
 
     $("#checkBox1",e).prop("checked", false);
     $("#checkBox2",e).prop("checked", new Function() {
         return Boolean.TRUE;
       }
     });
-    assertEquals(true, $("#checkBox2",e).prop("checked"));
-    assertEquals(false, $("#checkBox1",e).prop("checked"));
+    assertEquals(Boolean.TRUE, $("#checkBox2",e).prop("checked"));
+    assertEquals(Boolean.FALSE, $("#checkBox1",e).prop("checked"));
 
     $(window).prop("foo", 234);
     assertEquals(234d, $(window).prop("foo"));