Change what canMakePayment() means (#806)

* Change what canMakePayment() means

During the F2F, we came to a consensus that "canMakePayment" means "the user agent supports the PMIs" - but it does not mean that there is a payment instrument set up. We concluded that we might add something to check if there is an active instrument in the future.

* Link abuse protection tests

Author: marcoscaceres

index.html

@@ -1202,7 +1202,9 @@ 
           then return <a>a promise rejected witha> an
           "<a>InvalidStateErrora>" <a>DOMExceptiona>.
           li>
-          <li>Optionally, at the <a>user agenta>'s discretion, return <a>a
+          <li data-tests=
+          "payment-request/payment-request-canmakepayment-method-protection.https.html">
+          Optionally, at the <a>user agenta>'s discretion, return <a>a
           promise rejected witha> a "<a>NotAllowedErrora>"
           <a>DOMExceptiona>.
             <p class="note" data-link-for="PaymentRequest">
@@ -1216,51 +1218,25 @@ 
               time period in which those calls were made.
             p>
           li>
-          <li>Let <var>promisevar> be <a>a new promisea>.
+          <li>Let <var>hasHandlerPromisevar> be <a>a new promisea>.
           li>
-          <li>Return <var>promisevar>, and perform the remaining steps <a>in
-          parallela>.
+          <li>Return <var>hasHandlerPromisevar>, and perform the remaining
+          steps <a>in parallela>.
           li>
           <li>For each <var>paymentMethodvar> tuple in
           <var>requestvar>.<a>[[\serializedMethodData]]a>:
             <ol>
               <li>Let <var>identifiervar> be the first element in the
               <var>paymentMethodvar> tuple.
               li>
-              <li>Let <var>datavar> be the result of <a data-cite=
-              "ECMASCRIPT#sec-json.parse">JSON-parsinga> the second element
-              in the <var>paymentMethodvar> tuple.
-              li>
-              <li>If required by the specification that defines the
-              <var>identifiervar>, then <a data-cite=
-              "WEBIDL#dfn-convert-ecmascript-to-idl-value">converta>
-              <var>datavar> to an IDL value. Otherwise, <a data-cite=
-              "WEBIDL#dfn-convert-ecmascript-to-idl-value">converta> to
-              <a data-cite="WEBIDL#idl-object">objecta>.
-              li>
-              <li>If conversion results in an <a data-cite=
-              "WEBIDL#dfn-exception">exceptiona> <var>errorvar>, reject
-              <var>promisevar> with <var>errorvar> and terminate this
+              <li>If there user agent has a <a>payment handlera> that support
+              handling payment requests for <var>identifiervar>, resolve
+              <var>hasHandlerPromisevar> with true and terminate this
               algorithm.
               li>
-              <li>Let <var>handlersvar> be a <a>lista> of registered
-              <a>payment handlersa> that are authorized and can handle
-              payment request for <var>identifiervar>.
-              li>
-              <li>For each <var>handlervar> in <var>handlersvar>:
-                <ol>
-                  <li>Let <var>canMakePaymentvar> be the result of running
-                  <var>handlervar>'s <a>steps to check if a payment can be
-                  madea> with <var>datavar>.
-                  li>
-                  <li>If <var>canMakePaymentvar> is true, resolve
-                  <var>promisevar> with true, and return.
-                  li>
-                ol>
-              li>
             ol>
           li>
-          <li>Resolve <var>promisevar> with false.
+          <li>Resolve <var>hasHandlerPromisevar> with false.
           li>
         ol>
       section>