JS: Add failing TRAP test for trailing comma

Author: asgerf

javascript/extractor/tests/json/input/array-trailing-comma.json

@@ -0,0 +1,6 @@
+{
+    "array": [
+        "foo",
+        "bar",
+    ]
+}

javascript/extractor/tests/json/output/trap/array-trailing-comma.json.trap

@@ -0,0 +1,15 @@
+#10000=@"/array-trailing-comma.json;sourcefile"
+files(#10000,"/array-trailing-comma.json")
+#10001=@"/;folder"
+folders(#10001,"/")
+containerparent(#10001,#10000)
+#10002=@"loc,{#10000},0,0,0,0"
+locations_default(#10002,#10000,0,0,0,0)
+hasLocation(#10000,#10002)
+#20000=*
+json_errors(#20000,"Error: Omitted elements are not allowed in JSON.")
+#20001=@"loc,{#10000},5,4,5,4"
+locations_default(#20001,#10000,5,4,5,4)
+hasLocation(#20000,#20001)
+numlines(#10000,6,0,0)
+filetype(#10000,"json")