JS: fix parsing of CallExpression arguments, require comma after spre…

…ad element

js/parse.go

@@ -1444,21 +1444,22 @@ func (p *Parser) parseArguments() (args Args) {
 	// assume we're on (
 	p.next()
 	args.List = make([]Arg, 0, 4)
-	for {
+	for p.tt != CloseParenToken && p.tt != ErrorToken {
 		rest := p.tt == EllipsisToken
 		if rest {
 			p.next()
 		}
-
-		if p.tt == CloseParenToken || p.tt == ErrorToken {
-			break
-		}
 		args.List = append(args.List, Arg{
 			Value: p.parseExpression(OpAssign),
 			Rest:  rest,
 		})
-		if p.tt == CommaToken {
-			p.next()
+		if p.tt != CloseParenToken {
+			if p.tt != CommaToken {
+				p.fail("arguments", CommaToken, CloseParenToken)
+				return
+			} else {
+				p.next() // CommaToken
+			}
 		}
 	}
 	p.consume("arguments", CloseParenToken)

js/parse_test.go

@@ -535,12 +535,12 @@ func TestParseError(t *testing.T) {
 		{"x=new.bad", "expected target instead of bad in new.target expression"},
 		{"x=import.bad", "expected meta instead of bad in import.meta expression"},
 		{"x=super", "expected [, (, or . instead of EOF in super expression"},
-		{"x=super(a", "expected ) instead of EOF in arguments"},
+		{"x=super(a", "expected , or ) instead of EOF in arguments"},
 		{"x=super[a", "expected ] instead of EOF in index expression"},
 		{"x=super.", "expected Identifier instead of EOF in dot expression"},
 		{"x=new super(b)", "expected [ or . instead of ( in super expression"},
 		{"x=import", "expected ( instead of EOF in import expression"},
-		{"x=import(5", "expected ) instead of EOF in arguments"},
+		{"x=import(5", "expected , or ) instead of EOF in arguments"},
 		{"x=new import(b)", "unexpected ( in expression"},
 		{"import", "expected String, Identifier, *, or { instead of EOF in import statement"},
 		{"import *", "expected as instead of EOF in import statement"},