Use ICU for ID_START and ID_CONTINUE for Unicode 9 data

src/unicode.h

Index: src/unicode.h
diff --git a/src/unicode.h b/src/unicode.h
index 1b98a472f20bf06de2aad75889f27732872864c0..ad7d218b259b9b2d28d4176301f98d49d5beebfb 100644
--- a/src/unicode.h
+++ b/src/unicode.h
@@ -172,12 +172,10 @@ class Utf8 {
 struct Uppercase {
   static bool Is(uchar c);
 };
-struct Lowercase {
-  static bool Is(uchar c);
-};
 struct Letter {
   static bool Is(uchar c);
 };
+#ifndef V8_INTL_START
 struct V8_EXPORT_PRIVATE ID_Start {
   static bool Is(uchar c);
 };
@@ -190,6 +188,7 @@ struct V8_EXPORT_PRIVATE WhiteSpace {
 struct V8_EXPORT_PRIVATE LineTerminator {
   static bool Is(uchar c);
 };
+#endif  // !V8_INTL_SUPPORT
 struct ToLowercase {
   static const int kMaxWidth = 3;
   static const bool kIsToLower = true;