some speed optimizations

plugins/ant/src/com/intellij/lang/ant/dom/AntDomElement.java

@@ -24,6 +24,7 @@ import com.intellij.psi.xml.XmlFile;
 import com.intellij.psi.xml.XmlTag;
 import com.intellij.util.xml.*;
 
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.NoSuchElementException;
@@ -89,6 +90,9 @@ public abstract class AntDomElement implements DomElement {
 
   public final Iterator<AntDomElement> getAntChildrenIterator() {
     final List<DomElement> children = DomUtil.getDefinedChildren(this, true, false);
+    if (children.size() == 0) {
+      return Collections.<AntDomElement>emptyList().iterator();
+    }
     final Iterator<DomElement> it = children.iterator();
     return new Iterator<AntDomElement>() {
       private DomElement myUnprocessedElement;

plugins/ant/src/com/intellij/lang/ant/dom/AntDomPropertyReference.java

@@ -144,6 +144,22 @@ public class AntDomPropertyReference extends PsiPolyVariantReferenceBase<PsiElem
     return super.handleElementRename(newElementName);
   }
 
+  public boolean isReferenceTo(PsiElement element) {
+    // optimization to exclude obvious variants
+    final DomElement domElement = AntDomReferenceBase.toDomElement(element);
+    if (domElement instanceof AntDomProperty) {
+      final AntDomProperty prop = (AntDomProperty)domElement;
+      final String propName = prop.getName().getRawText();
+      if (propName != null && prop.getPrefix().getRawText() == null && prop.getEnvironment().getRawText() == null) {
+        // if only 'name' attrib is specified  
+        if (!propName.equalsIgnoreCase(getCanonicalText())) {
+          return false;
+        }
+      }
+    }
+    return super.isReferenceTo(element);
+  }
+
   private static class MyResolveResult implements ResolveResult {
 
     private final PsiElement myElement;