Remove input arrows for send screen amount row on firefox.

ui/app/components/send/currency-display.js

@@ -118,6 +118,7 @@ CurrencyDisplay.prototype.render = function () {
     readOnly = false,
     inError = false,
     onBlur,
+    step,
   } = this.props
   const { valueToRender } = this.state
 
@@ -152,6 +153,7 @@ CurrencyDisplay.prototype.render = function () {
             width: this.getInputWidth(valueToRender, readOnly),
           },
           min: 0,
+          step,
         }),
 
         h('span.currency-display__currency-symbol', primaryCurrency),

ui/app/components/send_/send-content/send-amount-row/send-amount-row.component.js

@@ -95,6 +95,7 @@ export default class SendAmountRow extends Component {
           primaryCurrency={primaryCurrency || 'ETH'}
           selectedToken={selectedToken}
           value={amount}
+          step={'any'}
         />
       </SendRowWrapper>
     )

ui/app/css/itcss/components/currency-display.scss

@@ -49,13 +49,19 @@
     flex: 1;
     max-width: 100%;
 
+    input[type="number"] {
+      -moz-appearance: textfield;
+    }
+
     input[type="number"]::-webkit-inner-spin-button {
       -webkit-appearance: none;
+      -moz-appearance: none;
       display: none;
     }
 
     input[type="number"]:hover::-webkit-inner-spin-button {
       -webkit-appearance: none;
+      -moz-appearance: none;
       display: none;
     }
   }
@@ -68,11 +74,13 @@
   .react-numeric-input {
     input[type="number"]::-webkit-inner-spin-button {
       -webkit-appearance: none;
+      -moz-appearance: none;
       display: none;
     }
 
     input[type="number"]:hover::-webkit-inner-spin-button {
       -webkit-appearance: none;
+      -moz-appearance: none;
       display: none;
     }
   }