[regexp] Add DotAll flag to regexp fuzzer

Teach the fuzzer about the new DotAll flag.

Bug: v8:6612
Change-Id: I92d6bfd920f5daef6733b1c547063ede718ecc8f
Reviewed-on: https://chromium-review.googlesource.com/832748Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50188}

test/fuzzer/regexp.cc

@@ -49,7 +49,7 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   static const int kAllFlags = i::JSRegExp::kGlobal | i::JSRegExp::kIgnoreCase |
                                i::JSRegExp::kMultiline | i::JSRegExp::kSticky |
-                               i::JSRegExp::kUnicode;
+                               i::JSRegExp::kUnicode | i::JSRegExp::kDotAll;
 
   const uint8_t one_byte_array[6] = {'f', 'o', 'o', 'b', 'a', 'r'};
   const i::uc16 two_byte_array[6] = {'f', 0xD83D, 0xDCA9, 'b', 'a', 0x2603};