V8_EXPORT is not required for public class templates, and using it may
lead to linker errors when users attempt to dllimport V8.

Change-Id: I0b2db2371d0fcbf50af94ba629670486b8f2bc00
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1757284Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63225}