Remove v8_context_snapshot.bin determinism hack.

Reverts parts of
https://chromium-review.googlesource.com/c/chromium/src/+/1293791 that should
no longer be needed after https://chromium-review.googlesource.com/c/1304441

Bug: 870584
Change-Id: I76fa59eb5c88c34cd222f2a40c983a4f4e615b27
Reviewed-on: https://chromium-review.googlesource.com/c/1328823Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Hitoshi Yoshida <peria@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606859}

third_party/blink/renderer/bindings/core/v8/v8_context_snapshot.cc

@@ -91,9 +91,6 @@ enum class InternalFieldType : uint8_t {
   kHTMLDocumentObject,
 };
 
-constexpr uintptr_t SerializedHTMLDocumentHack =
-    (uintptr_t)((unsigned)InternalFieldType::kHTMLDocumentType << 3u);
-
 const WrapperTypeInfo* FieldTypeToWrapperTypeInfo(InternalFieldType type) {
   switch (type) {
     case InternalFieldType::kNone:
@@ -326,15 +323,13 @@ v8::StartupData V8ContextSnapshot::SerializeInternalField(
   InternalFieldType field_type = InternalFieldType::kNone;
   const WrapperTypeInfo* wrapper_type = ToWrapperTypeInfo(object);
   if (kV8DOMWrapperObjectIndex == index) {
-    if ((uintptr_t)wrapper_type == SerializedHTMLDocumentHack ||
-        blink::V8HTMLDocument::wrapperTypeInfo.Equals(wrapper_type)) {
+    if (blink::V8HTMLDocument::wrapperTypeInfo.Equals(wrapper_type)) {
       field_type = InternalFieldType::kHTMLDocumentObject;
     }
     DCHECK_LE(kV8DefaultWrapperInternalFieldCount,
               object->InternalFieldCount());
   } else if (kV8DOMWrapperTypeIndex == index) {
-    if ((uintptr_t)wrapper_type == SerializedHTMLDocumentHack ||
-        blink::V8HTMLDocument::wrapperTypeInfo.Equals(wrapper_type)) {
+    if (blink::V8HTMLDocument::wrapperTypeInfo.Equals(wrapper_type)) {
       field_type = InternalFieldType::kHTMLDocumentType;
     } else if (blink::V8Document::wrapperTypeInfo.Equals(wrapper_type)) {
       field_type = InternalFieldType::kDocumentType;
@@ -496,12 +491,8 @@ void V8ContextSnapshot::TakeSnapshotForWorld(v8::SnapshotCreator* creator,
     v8::Local<v8::Object> document_wrapper = CreatePlainWrapper(
         isolate, world, context, &V8HTMLDocument::wrapperTypeInfo);
     int indices[] = {kV8DOMWrapperObjectIndex, kV8DOMWrapperTypeIndex};
-    // TODO(https://crbug.com/870584): Once v8 no longer writes pointers
-    // that have explicit serialization code into the snapshot, put
-    // const_cast<WrapperTypeInfo*>(&V8HTMLDocument::wrapperTypeInfo)
-    // here and remove the SerializedHTMLDocumentHack instances in
-    // SerializeEmbedderFields().
-    void* values[] = {nullptr, (void*)SerializedHTMLDocumentHack};
+    void* values[] = {nullptr, const_cast<WrapperTypeInfo*>(
+                                   &V8HTMLDocument::wrapperTypeInfo)};
     document_wrapper->SetAlignedPointerInInternalFields(base::size(indices),
                                                         indices, values);