BlinkMemoryMgt: Annotate the 2 classes of xml and xmlhttprequest with the macros of Allocator

The OnionSoup effort has a goal of allocating all garbage-collectable Blink objects
with Oilpan or PartitionAlloc. However, the some classes of //blink/renderer/core/xml
and //blink/renderer/core/xmlhttprequest have not yet been allocated with them so far.
So their uses of non-garbage-collected objects should be restricted to cases where the
garbage collector can discover their references. The macros of Allocator will be useful
for the non-garbage-collected objects to avoid unintended allocations.

After some analyzes, it was concluded that for the case of XMLParserContent class, it makes
sense to use USING_FAST_MALLOC because it has been used with scoped_refptr<>

In DeferredEvent class case, it makes sense to use DISALLOW_NEW because it has been used
by a member variable with a reference.

Bug: 919389
Change-Id: I18da5a1078b91caec8ad69c338ef874c9395f7e5
Reviewed-on: https://chromium-review.googlesource.com/c/1482280Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Gyuyoung Kim <gyuyoung@igalia.com>
Cr-Commit-Position: refs/heads/master@{#634651}

third_party/blink/renderer/core/xml/parser/xml_document_parser.h

@@ -36,6 +36,7 @@
 #include "third_party/blink/renderer/platform/heap/handle.h"
 #include "third_party/blink/renderer/platform/loader/fetch/resource_client.h"
 #include "third_party/blink/renderer/platform/text/segmented_string.h"
+#include "third_party/blink/renderer/platform/wtf/allocator.h"
 #include "third_party/blink/renderer/platform/wtf/compiler.h"
 #include "third_party/blink/renderer/platform/wtf/hash_map.h"
 #include "third_party/blink/renderer/platform/wtf/ref_counted.h"
@@ -52,6 +53,8 @@ class LocalFrameView;
 class Text;
 
 class XMLParserContext : public RefCounted<XMLParserContext> {
+  USING_FAST_MALLOC(XMLParserContext);
+
  public:
   static scoped_refptr<XMLParserContext>
   CreateMemoryParser(xmlSAXHandlerPtr, void* user_data, const CString& chunk);

third_party/blink/renderer/core/xmlhttprequest/xml_http_request_progress_event_throttle.h

@@ -30,6 +30,7 @@
 #include "base/memory/scoped_refptr.h"
 #include "third_party/blink/renderer/platform/heap/handle.h"
 #include "third_party/blink/renderer/platform/timer.h"
+#include "third_party/blink/renderer/platform/wtf/allocator.h"
 #include "third_party/blink/renderer/platform/wtf/forward.h"
 
 namespace blink {
@@ -98,6 +99,8 @@ class XMLHttpRequestProgressEventThrottle final
   // ProgressEvent dispatching. This class represents such a deferred
   // "progress" ProgressEvent.
   class DeferredEvent {
+    DISALLOW_NEW();
+
    public:
     DeferredEvent();
     void Set(bool length_computable,