Removed mutual modifier restriction for abstract static class.

Improved a couple of static class tests per feedback.

Author: Bilge

Zend/tests/static_class/inherit_static_class.phpt

@@ -3,8 +3,15 @@ Tests that a static class can inherit from another static class
 --FILE--
 <?php
 
-static class C {}
+static class C {
+    static function F() {
+        echo 'OK';
+    }
+}
 
 static class C2 extends C {}
+
+C2::F();
 ?>
 --EXPECT--
+OK

Zend/tests/static_class/static_abstract_class.phpt

@@ -1,9 +1,19 @@
 --TEST--
-Tests that a static class cannot be marked abstract
+Tests that a static class can be marked abstract
 --FILE--
 <?php
 
-abstract static class C {}
+abstract static class C {
+    abstract static function F();
+}
+
+static class C2 extends C {
+    static function F() {
+        echo 'OK';
+    }
+}
+
+C2::F();
 ?>
---EXPECTF--
-Fatal error: Cannot use the static modifier on an abstract class in %s on line %d
+--EXPECT--
+OK

Zend/tests/static_class/static_class_ast_export.phpt

@@ -0,0 +1,13 @@
+--TEST--
+Tests that the AST export of a static class includes the static modifier
+--FILE--
+<?php
+
+assert(false && function () {
+    static class C {}
+});
+?>
+--EXPECTF--
+%a
+%wstatic class C {%w}
+%a

Zend/tests/static_class/static_final_class.phpt

@@ -4,5 +4,8 @@ Tests that a static class can be marked final
 <?php
 
 final static class C {}
+
+static class C2 extends C {}
 ?>
---EXPECT--
+--EXPECTF--
+Fatal error: Class C2 cannot extend final class C in %s on line %d

Zend/zend_compile.c

@@ -944,15 +944,9 @@ uint32_t zend_add_class_modifier(uint32_t flags, uint32_t new_flag) /* {{{ */
 			"Cannot use the final modifier on an abstract class", 0);
 		return 0;
 	}
-	if (new_flags & ZEND_ACC_STATIC) {
-		if (new_flags & ZEND_ACC_EXPLICIT_ABSTRACT_CLASS) {
-			zend_throw_exception(zend_ce_compile_error, "Cannot use the static modifier on an abstract class", 0);
-			return 0;
-		}
-		if (new_flags & ZEND_ACC_READONLY_CLASS) {
-			zend_throw_exception(zend_ce_compile_error, "Cannot use the static modifier on a readonly class", 0);
-			return 0;
-		}
+	if ((new_flags & ZEND_ACC_STATIC) && (new_flags & ZEND_ACC_READONLY_CLASS)) {
+		zend_throw_exception(zend_ce_compile_error, "Cannot use the static modifier on a readonly class", 0);
+		return 0;
 	}
     if ((flags & ZEND_ACC_STATIC) && (new_flag & ZEND_ACC_STATIC)) {
 		zend_throw_exception(zend_ce_compile_error,