[dartfuzz] Handle more types in minimized literal generation.

Previously, the minimizer only handled a small, handpicked set of types
when replacing expressions with minimized literals of the expression's
type. This CL adds minimal literal generation for any type that has a
known constructor and generalizes handling of lists, sets, and maps.

TEST=dartfuzz

Change-Id: Ifeaacfd4dec1ba8f66f4fee9cf8c7fb74193b0d2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403861
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>

runtime/tools/dartfuzz/minimize.py

@@ -139,7 +139,7 @@ def generate_dart(dartfuzz_cmd, dart_test, smask, mask, do_expr):
         p = subprocess.Popen(cmds, stdout=subprocess.PIPE)
     p_stdout, p_stderr = p.communicate()
     if p.returncode != 0:
-        raise 'Invalid return code on generate %d' % p.returncode
+        raise RuntimeError('Invalid return code on generate %d' % p.returncode)
     mask_new = 0
     if do_expr:
         mask_new = int(p_stdout.decode().splitlines()[EXPRESSION_MASK_LINE])