[regexp] implement character classes for unicode regexps.

src/ostreams.h

Index: src/ostreams.h
diff --git a/src/ostreams.h b/src/ostreams.h
index 56f4aa7e45b766392699c6d36e49793071f0989d..1c2f38a1539e6ed42736a5f8b6ae82200f27c367 100644
--- a/src/ostreams.h
+++ b/src/ostreams.h
@@ -50,6 +50,12 @@ struct AsUC16 {
 };
 
 
+struct AsUC32 {
+  explicit AsUC32(int32_t v) : value(v) {}
+  int32_t value;
+};
+
+
 struct AsReversiblyEscapedUC16 {
   explicit AsReversiblyEscapedUC16(uint16_t v) : value(v) {}
   uint16_t value;
@@ -73,6 +79,10 @@ std::ostream& operator<<(std::ostream& os, const AsEscapedUC16ForJSON& c);
 // of printable ASCII range.
 std::ostream& operator<<(std::ostream& os, const AsUC16& c);
 
+// Writes the given character to the output escaping everything outside
+// of printable ASCII range.
+std::ostream& operator<<(std::ostream& os, const AsUC32& c);
+
 }  // namespace internal
 }  // namespace v8