src: do not set value on void return value

[zcbenz]

V8 added a static assertion to forbid it:

../../node/deps/v8/include/v8-function-callback.h:402:17: error: static assertion failed due to requirement '!std::is_void<void>::value': ReturnValue<void>::Set(const Local<S>) is deprecated. Do nothing to indicate that the operation succeeded or use SetFalse() to indicate that the operation failed (don't forget to handle info.ShouldThrowOnError()). See http://crbug.com/348660658 for details.
  402 |   static_assert(!std::is_void<T>::value,
      |                 ^~~~~~~~~~~~~~~~~~~~~~~
../../node/src/node_webstorage.cc:576:27: note: in instantiation of function template specialization 'v8::ReturnValue<void>::Set<v8::Value>' requested here
  576 |     info.GetReturnValue().Set(value);
      |                           ^

The assertion needs a newer version of clang to work so the official CI is not hit by it.

This commit also includes a change to GN file to fix GN build failure after V8 upgrade.

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61225/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.32%. Comparing base (4f94397) to head (9b3436e).
Report is 31 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #54449   +/-   ##
=======================================
  Coverage   87.31%   87.32%           
=======================================
  Files         648      648           
  Lines      182321   182319    -2     
  Branches    34969    34969           
=======================================
+ Hits       159196   159210   +14     
+ Misses      16396    16385   -11     
+ Partials     6729     6724    -5     

Files	Coverage Δ
src/node_webstorage.cc	73.51% <100.00%> (-0.14%)	⬇️

... and 16 files with indirect coverage changes

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61252/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61261/

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/61263/

[targos]

I opened an alternative PR at #54418.

The assertion needs a newer version of clang to work so the official CI is not hit by it.

I don't think that's why official CI is not hit by it. The assertion is behind V8_IMMINENT_DEPRECATION_WARNINGS, which we don't set.