deps: V8: cherry-pick 53e62af

Original commit message:

[build] Include string in v8.h

Explicitly #include<string> in v8.h, since std::string is referenced
in it. In the C++ STL shipped with Visual Studio 2019, none of the
headers included in v8.h ends up including the C++ string header, which
caused a compile error.

Bug: v8:9793
Change-Id: I84a133dd10dd6dcc7b70287af393e82cf0dc97df
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1834321
Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64074}

Refs: https://github.com/v8/v8/commit/53e62affd33ad036a169eff7d6c1d50b0adcd21a