Add ES6 SingleLineHTMLOpenComment support ("<!--").

src-input/duk_lexer.c

@@ -1256,7 +1256,21 @@ void duk_lexer_parse_js_input_element(duk_lexer_ctx *lex_ctx,
 		advtok = DUK__ADVTOK(1, DUK_TOK_COMMA);
 		break;
 	case DUK_ASC_LANGLE:  /* '<' */
-		if (DUK__L1() == DUK_ASC_LANGLE && DUK__L2() == DUK_ASC_EQUALS) {
+		if (DUK__L1() == DUK_ASC_EXCLAMATION && DUK__L2() == DUK_ASC_MINUS && DUK__L3() == DUK_ASC_MINUS) {
+			/*
+			 *  ES6: B.1.3, handle "<!--" SingleLineHTMLOpenComment
+			 */
+
+			/* DUK__ADVANCECHARS(lex_ctx, 4) would be correct here, but it is unnecessary */
+			for (;;) {
+				x = DUK__L0();
+				if (x < 0 || duk_unicode_is_line_terminator(x)) {
+					break;
+				}
+				DUK__ADVANCECHARS(lex_ctx, 1);
+			}
+			goto restart;  /* line terminator will be handled on next round */
+		} else if (DUK__L1() == DUK_ASC_LANGLE && DUK__L2() == DUK_ASC_EQUALS) {
 			advtok = DUK__ADVTOK(3, DUK_TOK_ALSHIFT_EQ);
 		} else if (DUK__L1() == DUK_ASC_EQUALS) {
 			advtok = DUK__ADVTOK(2, DUK_TOK_LE);