[PR] Fixes a bug with the currency amount validation

This CL fixes a bug where the value of the currency amount was being
checked against the maximum allowed string length not the length of the
value string.

Bug: 806666
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I8897c93f06e8cb590c5414497b53ab87fa291e77
Reviewed-on: https://chromium-review.googlesource.com/895546Reviewed-by: Rouslan Solomakhin <rouslan@chromium.org>
Commit-Queue: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533317}

ios/chrome/browser/web/resources/payment_request.js

@@ -182,7 +182,8 @@ var SerializedPaymentResponse;
       amount, amountName) {
     // Convert the value to String if it isn't already one.
     amount.value = String(amount.value);
-    if (amount.value > __gCrWeb['paymentRequestManager'].MAX_STRING_LENGTH) {
+    if (amount.value.length >
+        __gCrWeb['paymentRequestManager'].MAX_STRING_LENGTH) {
       throw new TypeError(
           amountName + ' value cannot be longer than ' +
           __gCrWeb['paymentRequestManager'].MAX_STRING_LENGTH + ' characters');