* chore: fix cpplint 'include_what_you_use' warnings
Typically by including <memory>, <utility> etc.
* chore: fix 'static/global string constant' warning
Use C style strings instead of std::string.
Style guide forbids non-trivial static / global variables. https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables
/home/charles/electron/electron-gn/src/electron/script/cpplint.js
* refactor: remove global string variables.
Fix 'global string variables are not permitted' linter warnings
by using the base::NoDestructor<> wrapper to make it explicit that
these variables are never destroyed.
The style guide's take on globals with nontrivial destructors:
https://google.github.io/styleguide/cppguide.html#Static_and_Global_Variables
* fix: initializer error introduced in last commit
* fix: remove WIP file that was included by accident
* fix: include order
* fix: include order
* fix: include order
* fix: include order, again
Chromium commit [03563dd163][1] changed the way that the
spellcheck-enabled status was checked, defaulting to false.
Added the first (!) test for spellchecking, too.
Fixes#13608.
[1]: 03563dd163
The class didn't save the V8 context for the spell checking JS function. When
it later tried to call the JS function and there was no active context, V8
crashed.
I also optimized the spell checking loop by introducing `SpellCheckScope` and
reusing the V8 handles throughout the whole loop.
