Add test case for "...attr" as attribute

Author: TimothyGu

test/cases/attrs-spread.expected.json

@@ -37,4 +37,12 @@
 {"type":"spread-attribute","line":7,"col":5,"val":"attrs","mustEscape":false}
 {"type":"end-attributes","line":9,"col":7}
 {"type":"newline","line":10,"col":1}
-{"type":"eos","line":10,"col":1}
+{"type":"tag","line":10,"col":1,"val":"div"}
+{"type":"start-attributes","line":10,"col":4}
+{"type":"attribute","line":10,"col":5,"name":"...attrs","val":true,"mustEscape":true}
+{"type":"spread-attribute","line":10,"col":16,"val":"attrs","mustEscape":true}
+{"type":"attribute","line":10,"col":26,"name":"...attrs","val":"'val'","mustEscape":true}
+{"type":"attribute","line":10,"col":44,"name":"...","val":true,"mustEscape":true}
+{"type":"end-attributes","line":10,"col":49}
+{"type":"newline","line":11,"col":1}
+{"type":"eos","line":11,"col":1}

test/cases/attrs-spread.pug

@@ -7,3 +7,4 @@ div(...!attrs)
 div(... 
 !
 	attrs)
+div("...attrs" ...attrs, '...attrs' ='val' "...")