Omitting deleteCount, this.splice() acts different from array.splice()

[4d4841]

Description

Should this.splice('thisArray', 0) remove all entries? "If deleteCount is omitted ... then all of the elements from start through the end of the array will be deleted." https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice

Live Demo

http://jsbin.com/wogogaseya/1/edit?html,output

Steps to Reproduce

    let arrgh = [1,2,3];
    this.arrgh = [1,2,3];
    arrgh.splice(0);
    this.splice('arrgh',0);
    console.log('Lengths:',arrgh.length,this.arrgh.length);

// Lengths: 0 3

https://github.com/Polymer/polymer/blob/master/lib/mixins/property-effects.html#L1942

Expected Results

Lengths: 0 0

Actual Results

Lengths: 0 3

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari 9
• Safari 8
• IE 11

Versions

• Polymer: vX.X.X
• webcomponents: vX.X.X

[kevinpschaaf]

Yes, the intention is that they match the native API, so that is an oversight.

@TimvdLippe do you want to take a crack at a fix for Polymer 2?