Avoid matching Newline in U16MatchAnyButNewline.

Summary:
The `U16MatchAnyButNewline` instruction is supposed to perform
the same `isLineTerminator` check that `MatchAnyButNewline` performs,
but it didn't.

Add the check and add a test.

Reviewed By: dulinriley

Differential Revision: D19146240

fbshipit-source-id: f3bae36ffec8398ba185992bc43f85b82bb37586

lib/Regex/Executor.cpp

@@ -969,9 +969,8 @@ auto Context<Traits>::match(State<Traits> *s, bool onlyAtStart)
           break;
 
         case Opcode::U16MatchAnyButNewline:
-          if (c.atEnd())
+          if (c.atEnd() || isLineTerminator(c.consumeUTF16()))
             BACKTRACK();
-          c.consumeUTF16();
           s->ip_ += sizeof(U16MatchAnyButNewlineInsn);
           break;
 

test/hermes/regexp_unicode.js

@@ -79,6 +79,12 @@ print(!! /^..$/u.exec("\u{1F600}"));
 print(!! /^.$/u.exec("\u{1F600}"));
 // CHECK-NEXT: true
 
+// Ensure that we don't match newlines with the dot.
+print(/.*/u.exec("abc\ndef"), "DONE");
+// CHECK-NEXT: abc DONE
+print(/.*/u.exec("\u0101bc\ndef")[0].length);
+// CHECK-NEXT: 3
+
 // Test advanceStringIndex.
 // We should not match a low surrogate in a Unicode regexp.
 print(!! /\uDE42/u.exec("\uD83D\uDE42ZZZ"));