Throw SyntaxError for identifier with supplementary character

Fix assertion failure issue #1871 on github.
Don't allow supplementary character as identifier start or part.

JerryScript-DCO-1.0-Signed-off-by: Sanggyu Lee sg5.lee@samsung.com

jerry-core/lit/lit-char-helpers.c

@@ -226,6 +226,14 @@ lit_char_is_identifier_start (const uint8_t *src_p) /**< pointer to a vaild UTF8
     return lit_char_is_identifier_start_character (*src_p);
   }
 
+  /* ECMAScript 2015 specification allows some code points in supplementary plane.
+   * However, we don't permit characters in supplementary characters as start of identifier.
+   */
+  if ((*src_p & LIT_UTF8_4_BYTE_MASK) == LIT_UTF8_4_BYTE_MARKER)
+  {
+    return false;
+  }
+
   return lit_char_is_identifier_start_character (lit_utf8_peek_next (src_p));
 } /* lit_char_is_identifier_start */
 
@@ -262,6 +270,14 @@ lit_char_is_identifier_part (const uint8_t *src_p) /**< pointer to a vaild UTF8
     return lit_char_is_identifier_part_character (*src_p);
   }
 
+  /* ECMAScript 2015 specification allows some code points in supplementary plane.
+   * However, we don't permit characters in supplementary characters as part of identifier.
+   */
+  if ((*src_p & LIT_UTF8_4_BYTE_MASK) == LIT_UTF8_4_BYTE_MARKER)
+  {
+    return false;
+  }
+
   return lit_char_is_identifier_part_character (lit_utf8_peek_next (src_p));
 } /* lit_char_is_identifier_part */