Merge remote-tracking branch 'mainline/develop' into pr-develop

app/code/Magento/Checkout/Controller/Cart/CouponPost.php

...nto/Checkout/Test/Unit/Controller/Cart/CouponPostTest.php

app/code/Magento/Eav/Model/AttributeManagement.php

...e/Magento/Eav/Test/Unit/Model/AttributeManagementTest.php

app/code/Magento/Sales/Model/Order/Payment.php

app/code/Magento/Sales/Test/Unit/Model/Order/PaymentTest.php

app/code/Magento/Swatches/Helper/Data.php

app/code/Magento/Swatches/Test/Unit/Helper/DataTest.php

...t/Model/ResourceModel/Widget/Instance/Options/ThemeId.php

...et/Model/ResourceModel/Widget/Instance/Options/Themes.php

...odel/ResourceModel/Widget/Instance/Options/ThemesTest.php

...view/adminhtml/layout/adminhtml_widget_instance_block.xml

...to_Checkout/web/css/source/module/checkout/_checkout.less

...end/Magento/blank/Magento_Rma/web/css/source/_module.less

...to_Checkout/web/css/source/module/checkout/_checkout.less

...tend/Magento/luma/Magento_Rma/web/css/source/_module.less

...t/Constraint/AssertAddedProductAttributeOnProductForm.php

...tests/app/Magento/Checkout/Test/Block/Onepage/Payment.php

...tests/app/Magento/Tax/Test/Handler/Curl/RemoveTaxRule.php

...Magento/Widget/Test/Block/Adminhtml/Widget/WidgetGrid.php