Ensure newer versions of jquery handle total amount properly
Ensure newer versions of jquery handle total amount properly

Without this patch, an attempt to submit a webform with a payment option
that totals $0 gets the error: Error: Could not find payment
information.

That's because the check for a total price of $0 fails. It fails for two
reasons:

1. Newer versions of jquery conform to html5 specs that say the data in
the field called "data-amount" should be referred to as simply "amount"
rather than "data-amount"

2. In addition, jquery now tries to convert values to their appropriate
type, so the strict matching of === '0' only matches on the string value
of '0' but jquery is converting the string '0' into the integer 0.

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