UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2863.0 Safari/537.36

Steps to reproduce the problem:
1.  Open https://sideshowbarker.net/tests/payment-request/invalid-value2.html in a build that has the PaymentRequest API enabled.

What is the expected behavior?
You should see this:

Test passes

The Payment Request API spec does not state what UAs must do if the value field of a PaymentCurrencyAmount is not syntactically valid. Specifically, the spec does not state that the UA must throw.

Called PaymentRequest constructor with value "x" for the value field:

    new PaymentRequest([{supportedMethods: ['foo']}], {total: {label: 'bar', amount: {currency: 'USD', value: 'x'}}})

... and as expected, browser did not throw.

What went wrong?
Instead of the expected behavior I get this:

Test fails

The Payment Request API spec does not state what UAs must do if the value field of a PaymentCurrencyAmount is not syntactically valid. Specifically, the spec does not state that the UA must throw.

Called PaymentRequest constructor with value "x" for the value field:

    new PaymentRequest([{supportedMethods: ['foo']}], {total: {label: 'bar', amount: {currency: 'USD', value: 'x'}}})

Expected browser to not throw, but instead browser threw:

    TypeError: Failed to construct 'PaymentRequest': 'x' is not a valid amount format

Did this work before? N/A 

Chrome version: 55.0.2863.0  Channel: canary
OS Version: OS X 10.11.6
Flash Version: 

The browser should not throw for 'x' or any other non-valid amount format, because the spec does not state any requirement for the browser to throw for that condition.