DescriptorFinder now can find class names in a package

This helps to get rid of "repeated class_name" field in Package protobuf
message. DescriptorFinder in resolve.java uses PSI to find all classes in a
package, and the finder for built-ins just reads .kotlin_class_names file

compiler/tests/org/jetbrains/jet/codegen/KotlinPackageAnnotationTest.java

@@ -55,9 +55,6 @@ public class KotlinPackageAnnotationTest extends CodegenTestCase {
 
         PackageData data = JavaProtoBufUtil.readPackageDataFrom(kotlinPackage.data());
 
-        Set<String> classNames = collectClassNames(data);
-        assertSameElements(Arrays.asList("A", "B", "C"), classNames);
-
         Set<String> callableNames = collectCallableNames(data);
         assertSameElements(Arrays.asList("foo", "bar", "C"), callableNames);
     }
@@ -71,13 +68,4 @@ public class KotlinPackageAnnotationTest extends CodegenTestCase {
         }
         return callableNames;
     }
-
-    @NotNull
-    private static Set<String> collectClassNames(@NotNull PackageData data) {
-        Set<String> classNames = new HashSet<String>();
-        for (int name : data.getPackageProto().getClassNameList()) {
-            classNames.add(data.getNameResolver().getName(name).asString());
-        }
-        return classNames;
-    }
 }