value of entity as a quick doc

#WEB-5022 fixed

xml/impl/src/com/intellij/xml/util/documentation/XmlDocumentationProvider.java

@@ -62,6 +62,10 @@ public class XmlDocumentationProvider implements DocumentationProvider {
     if (element instanceof SchemaPrefix) {
       return ((SchemaPrefix)element).getQuickNavigateInfo();
     }
+    if (element instanceof XmlEntityDecl) {
+      final XmlAttributeValue value = ((XmlEntityDecl)element).getValueElement();
+      return value != null ? value.getText() : null;
+    }
     return null;
   }
 

xml/tests/src/com/intellij/codeInsight/XmlDocumentationTest.java

@@ -74,6 +74,11 @@ public class XmlDocumentationTest extends LightPlatformCodeInsightFixtureTestCas
     assertEquals("XML Namespace Prefix \"xs\" (http://www.w3.org/2001/XMLSchema)", context.getQuickNavigateInfo());
   }
 
+  public void testEntityValue() throws Exception {
+    DocumentationTestContext context = new DocumentationTestContext("9.xml");
+    assertEquals("\"«\"", context.getQuickNavigateInfo());
+  }
+
   public void testXmlDoc6() throws Exception {
     final String testName = getTestName(false);
     doQuickDocGenerationTestWithCheckExpectedResult((Object)"car",testName + ".xml", testName + ".xsd");