Add test case of function parameter list

Author: bannzai

test/Frontend/emit-syntax.swift

@@ -37,6 +37,23 @@ func Bar(arg1: String, arg2: Int) {
 // CHECK: "kind":"r_brace"
 }
 
+// CHECK: "kind":"kw_func"
+// CHECK: "text":"CheckParameterList"
+// CHECK: "kind":"l_paren"
+// CHECK: "text":"arg1"
+// CHECK: "text":"String"
+// CHECK: "kind":"ellipsis"
+// CHECK: "presence":"Present"}
+// CHECK: null
+// CHECK: "kind":"comma"
+// CHECK: "text":"arg2"
+// CHECK: "text":"Int"
+// CHECK: "kind":"r_paren"
+// CHECK: "kind":"l_brace"
+func CheckParameterList(arg1: String..., arg2: Int) {
+// CHECK: "kind":"r_brace"
+}
+
 // CHECK: "leadingTrivia":[
 // CHECK: "kind":"LineComment",
 // CHECK: "value":"\/\/ Comment at the end of the file"