[CFE] Fuzzer using Dart.G

This is the first commit of this effort. It's not polished and mostly
generates nonsense output that, though, should not crash the compiler.
Further work might add options to create less-nonsense output).

Change-Id: Ic7f140ea6f248bfa9a0e62ca37326def1d0a5086
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403601
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>

pkg/front_end/test/spell_checking_list_tests.txt

@@ -38,6 +38,8 @@ amend
 amended
 amortized
 analyses
+analytics
+analyzerinput
 andahalf
 animal
 animated
@@ -126,6 +128,7 @@ ca
 cafebabe
 calloc
 camel
+cap
 capacity
 capitalized
 caption
@@ -202,6 +205,7 @@ ctrl
 cumulative
 cursor
 cuts
+cutting
 cx
 da
 dacoharkes
@@ -246,6 +250,7 @@ di
 diagnosticable
 dictionaries
 dictionary
+dicy
 differentiate
 dijkstra
 dijkstras
@@ -314,6 +319,7 @@ exercised
 exercises
 exitcode
 exiting
+exotic
 expanded
 expansive
 explainer
@@ -349,6 +355,7 @@ foos
 forbidden
 forces
 foreground
+forever
 forgot
 forrest
 forth
@@ -367,6 +374,7 @@ futu
 futures
 fuzz
 fuzzed
+fuzzer
 fuzzing
 fx
 gallery
@@ -469,6 +477,7 @@ jc
 jk
 jlcontreras
 joo
+jsonrpc
 jumped
 kernels
 kitty
@@ -491,12 +500,14 @@ lints
 listening
 listing
 ln
+locale
 locating
 logd
 logs
 loo
 lookahead
 loopback
+lsp
 ma
 mac
 maker
@@ -513,6 +524,7 @@ micro
 migrations
 mimicking
 minimize
+minimized
 minimizer
 minimizing
 minitest
@@ -559,6 +571,7 @@ nondefault
 nonexisting
 noo
 noted
+notification
 noting
 nottest
 nq
@@ -590,12 +603,14 @@ oracle
 ot
 outbound
 outliers
+outstanding
 overflows
 overhead
 overlay
 overly
 ox
 pack
+packet
 paging
 paint
 parallax
@@ -678,13 +693,15 @@ refname
 refusing
 regards
 regenerate
+regex
 regressions
 reify
 reject
 relinked
 remap
 remapping
 remaps
+removeable
 rendition
 reorder
 reordering
@@ -727,6 +744,7 @@ sdkroot
 sdks
 secondary
 secondtest
+secure
 seemingly
 segment
 selection
@@ -752,6 +770,7 @@ sigwinch
 silence
 simplistic
 slashes
+sleep
 slight
 sliver
 smoke
@@ -773,6 +792,7 @@ spurious
 sqrt
 squared
 ss
+ssls
 sssp
 stacks
 stashed
@@ -788,6 +808,7 @@ stringy
 strip
 strongest
 stub's
+stuck
 stupid
 subcommand
 subdir
@@ -813,6 +834,7 @@ tails
 taskset
 te
 templates
+testfile
 theoretically
 there'll
 thereby
@@ -889,6 +911,7 @@ vf
 virtually
 visualization
 vp
+vscode
 vt
 vte
 waited
@@ -906,6 +929,7 @@ wins
 wording
 workers
 workflow
+workspace
 worlds
 worse
 wrongly