-Wattributes warnings from AtomString.cpp and WTFString.cpp

[Michael Catanzaro]

https://github.com/WebKit/WebKit/pull/474 introduced some new build warnings:

[109/2539] Building CXX object Source/WTF/wtf/CMakeFiles/WTF.dir/text/AtomString.cpp.o
/home/mcatanzaro/Projects/WebKit/Source/WTF/wtf/text/AtomString.cpp:35:43: warning: ‘visibility’ attribute ignored [-Wattributes]
   35 | WTF_EXPORT_PRIVATE const StaticAtomString nullAtomData { nullptr };
      |                                           ^~~~~~~~~~~~
/home/mcatanzaro/Projects/WebKit/Source/WTF/wtf/text/AtomString.cpp:36:43: warning: ‘visibility’ attribute ignored [-Wattributes]
   36 | WTF_EXPORT_PRIVATE const StaticAtomString emptyAtomData { &StringImpl::s_emptyAtomString };
      |                                           ^~~~~~~~~~~~~
[144/2539] Building CXX object Source/WTF/wtf/CMakeFiles/WTF.dir/text/WTFString.cpp.o
/home/mcatanzaro/Projects/WebKit/Source/WTF/wtf/text/WTFString.cpp:638:39: warning: ‘visibility’ attribute ignored [-Wattributes]
  638 | WTF_EXPORT_PRIVATE const StaticString nullStringData { nullptr };
      |                                       ^~~~~~~~~~~~~~
/home/mcatanzaro/Projects/WebKit/Source/WTF/wtf/text/WTFString.cpp:639:39: warning: ‘visibility’ attribute ignored [-Wattributes]
  639 | WTF_EXPORT_PRIVATE const StaticString emptyStringData { &StringImpl::s_emptyAtomString };
      |                                       ^~~~~~~~~~~~~~~

[Michael Catanzaro]

Ah, it's redundant because it's already specified in the header file. We can just remove it. Easy.

[Michael Catanzaro]

Pull request: https://github.com/WebKit/WebKit/pull/604

[EWS]

Committed r294139 (250509@main): <https://commits.webkit.org/250509@main>

Reviewed commits have been landed. Closing PR #604 and removing active labels.

[Radar WebKit Bug Importer]

<rdar://problem/93216876>