Use fine-grained v8 headers.

Include specific v8-foo.h files instead of v8.h. Resolve IWYU issues to
fix the build.

Bug: v8:11965
Change-Id: I19bc2393383d0d867d87ed1b96ecb8de92b76078
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/94991
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Nigi <nigi@chromium.org>
diff --git a/testing/v8_initializer.cpp b/testing/v8_initializer.cpp
index d789278..bf672bf 100644
--- a/testing/v8_initializer.cpp
+++ b/testing/v8_initializer.cpp
@@ -11,7 +11,8 @@
 #include "testing/utils/path_service.h"
 #include "third_party/base/numerics/safe_conversions.h"
 #include "v8/include/libplatform/libplatform.h"
-#include "v8/include/v8.h"
+#include "v8/include/v8-initialization.h"
+#include "v8/include/v8-snapshot.h"
 
 #ifdef PDF_ENABLE_XFA
 #include "v8/include/cppgc/platform.h"