Fix NPE when a resolving a class that didn't have a specialization. (See issue #936.)

Author: EricBishton

src/common/com/intellij/plugins/haxe/lang/psi/HaxeResolver.java

@@ -430,7 +430,9 @@ private static List<? extends PsiElement> resolveByClassAndSymbol(@Nullable Haxe
       if (leftClass.isAbstract()) {
         HaxeAbstractClassModel model = (HaxeAbstractClassModel)leftClass.getModel();
         if (model.isForwarded(reference.getReferenceName())) {
-          final HaxeClass underlyingClass = model.getUnderlyingClass(reference.getSpecialization().toGenericResolver(leftClass));
+          HaxeGenericSpecialization specialization = reference.getSpecialization();
+          HaxeGenericResolver resolver = specialization != null ? specialization.toGenericResolver(leftClass) : null;
+          final HaxeClass underlyingClass = model.getUnderlyingClass(resolver);
           if (underlyingClass != null) {
             member = underlyingClass.getModel().getMember(reference.getReferenceName());
             if (member != null) {