[webkit-dev] Reminder: include everything that you use in implementation files

[Brian Burg]

Hello folks,

I'd like to remind everyone to please include what you use in .cpp,  .mm, and other files. When reviewing patches, please
ensure that new mentions of classes, structs, etc. within an implementation file have a corresponding header include. 
All of our headers have #pragma once, so there is no downside to being more explicit.

I've been noticing an uptick in the number of unified sources-related build failures. I can't remember the last nontrivial patch
I wrote that did *not* include unrelated build fixes. Typically these failures aren't found until EWS results come back, reducing developer velocity.
And obviosuly it's super annoying to encounter completely unrelated build failures that must be nonetheless addressed.

Let's all do our part so that hacking on WebKit remains delightful.

Thanks,

Brian Burg (he/they)
 WebKit Developer Experience