Kernel: Split VMObject into two classes: Anonymous- and InodeVMObject

InodeVMObject is a VMObject with an underlying Inode in the filesystem.
AnonymousVMObject has no Inode.

I'm happy that InodeVMObject::inode() can now return Inode& instead of
VMObject::inode() return Inode*. :^)

Kernel/VM/AnonymousVMObject.cpp

@@ -0,0 +1,41 @@
+#include <Kernel/VM/AnonymousVMObject.h>
+#include <Kernel/VM/PhysicalPage.h>
+
+NonnullRefPtr<AnonymousVMObject> AnonymousVMObject::create_with_size(size_t size)
+{
+    size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
+    return adopt(*new AnonymousVMObject(size));
+}
+
+NonnullRefPtr<AnonymousVMObject> AnonymousVMObject::create_for_physical_range(PhysicalAddress paddr, size_t size)
+{
+    size = ceil_div(size, PAGE_SIZE) * PAGE_SIZE;
+    return adopt(*new AnonymousVMObject(paddr, size));
+}
+
+AnonymousVMObject::AnonymousVMObject(size_t size)
+    : VMObject(size, ShouldFillPhysicalPages::Yes)
+{
+}
+
+AnonymousVMObject::AnonymousVMObject(PhysicalAddress paddr, size_t size)
+    : VMObject(size, ShouldFillPhysicalPages::No)
+{
+    for (size_t i = 0; i < size; i += PAGE_SIZE)
+        m_physical_pages.append(PhysicalPage::create(paddr.offset(i), false, false));
+    ASSERT(m_physical_pages.size() == page_count());
+}
+
+AnonymousVMObject::AnonymousVMObject(const AnonymousVMObject& other)
+    : VMObject(other)
+{
+}
+
+AnonymousVMObject::~AnonymousVMObject()
+{
+}
+
+NonnullRefPtr<VMObject> AnonymousVMObject::clone()
+{
+    return adopt(*new AnonymousVMObject(*this));
+}