These instances were detected by searching for files that include
AK/Format.h, but don't match the regex:
\\b(CheckedFormatString|critical_dmesgln|dbgln|dbgln_if|dmesgln|FormatBu
ilder|__FormatIfSupported|FormatIfSupported|FormatParser|FormatString|Fo
rmattable|Formatter|__format_value|HasFormatter|max_format_arguments|out
|outln|set_debug_enabled|StandardFormatter|TypeErasedFormatParams|TypeEr
asedParameter|VariadicFormatParams|v_critical_dmesgln|vdbgln|vdmesgln|vf
ormat|vout|warn|warnln|warnln_if)\\b
(Without the linebreaks.)
This regex is pessimistic, so there might be more files that don't
actually use any formatting functions.
Observe that this revealed that Userland/Libraries/LibC/signal.cpp is
missing an include.
In theory, one might use LibCPP to detect things like this
automatically, but let's do this one step after another.
This patch adds contexts to line iterator for nesting list items and
blockquotes. It also incidentally makes the api for LineIterator
simpler, and will make it easier to add other containers in the future.
