Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
Although this is only known to affect buttons with builtin child widgets, it is difficult to audit all GTK widgets for similar situations, and so the same defense is applied to all widgets.
The style context for MOZ_GTK_TEXT_VIEW is now created by copying from the widget instead of caching a widget and using its context.
No rendering changes are expected, unless themes are animating GtkTextView backgrounds.
