<template if> evaluating all expressions twice

[esprehn]

<polymer-element name="ex-ample">
    <template>
        <template if="{{ item }}">
            {{ item.created | formatDate }}
        </template>
    </template>
    <script>
        Polymer("ex-ample", {
            item: {created: new Date()},
            formatDate: function(date) {
                console.log(date);
                return "";
            },
        });
    </script>
</polymer-element>
<ex-ample></ex-ample>

if you open the console you'll see the date value logged twice. If you put a custom element inside the <template if> with a console.log in the created callback it only prints once so it's not stamping twice, but it does evaluate all the binding values twice even though nothing has changed.

This is with Object.observe and Experimental Web Platform Features turned on.

[sjmiles]

@rafaelw

[rafaelw]

This was a polymer-expressions bug. Fixed here: googlearchive/polymer-expressions@e0a6646